Dissertations / Theses on the topic 'Volatile organic compound degradation'

Les composés organiques volatils oxygénés (COVO), principalement émis par des sources biogènes, jouent un rôle majeur dans la chimie de l'atmosphère, le changement climatique, l'environnement et la santé. Il a été récemment démontré que ces émissions augmentent en cas de stress biotique et/ou abiotique. Les COVO biogéniques peuvent subir une variété de réactions, tant chimiques que photolytiques, et ils sont impliqués dans la formation d'Aérosols Organiques Secondaires (AOS). Ces composés ont été détectés dans diverses régions, mais il y a très peu d’informations sur leurs processus de dégradation sous conditions troposphériques. La compréhension des mécanismes d'oxydation de ces espèces est d'un intérêt fondamental et fournit des données cruciales pour les modèles atmosphériques qui sont utilisés par les responsables politiques pour formuler et décider des stratégies d'amélioration de la qualité de l'air. Cette thèse vise à améliorer les connaissances actuelles sur le comportement de ces COVO, pour une meilleure compréhension de leur impact sur la chimie atmosphérique. Dans ce travail, nous avons présenté une étude détaillée de la dégradation atmosphérique des aldéhydes insaturés en C5-C7 et des alcools insaturés en C5-C8 par ozone, l’atome Cl et le radical OH. Les principaux objectifs étaient de mieux comprendre le mécanisme de réaction et de mettre en évidence leur potentiel à former des AOS. Pour atteindre ces objectifs, nous nous sommes concentrés sur quatres volets : (i) détermination du spectre IR et UV des aldéhydes insaturés en C5-C7, (ii) détermination de la constante de vitesse pour les systèmes COVO + Oxydant étudiés à température ambiante, (iii) identification et quantification des produits en phase gazeuse, (iv) détermination des rendements en AOS. Les études sur les produits ont été menées avec et sans ajout d'un piégeur des radicaux OH. Les expériences ont été réalisées dans huit réacteurs différents, statiques (chambres) ou dynamiques (flux), et diverses techniques analytiques ont été utilisées pour étudier les produits de réaction (FTIR, GC-FID/MS, SPME-GC/MS, HPLC, PTR-ToF-MS, SIFT-MS, PLP-LIF) et la formation de SOA (SMPS, FMPS)
Oxygenated Volatile Organic Compounds (OVOCs), mainly released from biogenic sources, play a major role in atmospheric chemistry, climate change, environment, and health. These emissions have been recently shown to increase in the case of biotic and/or abiotic stresses. Biogenic OVOCs may undergo a wide variety of reactions, both chemical and photolytic, and they contribute in the formation of Secondary Organic Aerosols (SOAs). These compounds have been detected in various areas, but little is known about their degradation processes under tropospheric conditions. Understanding the oxidation mechanisms of these species is of fundamental interest and yields crucial data for atmospheric models used by policymakers in formulating and deciding strategies for improving air quality. This dissertation aims to improve the current knowledge of those OVOCs behaviors to better understand their impact on atmospheric chemistry. This work reports a detailed study of the atmospheric degradation of C5-C7 unsaturated aldehydes and C5-C8 unsaturated alcohols by ozone, Cl atom, and OH radical. The main objectives were to better understand the reaction mechanism and to feature the SOA formation potential. To achieve these objectives, we focused on four topics: (i) determination of IR and UV spectrum of C5-C7 unsaturated aldehydes, (ii) determination of the rate constant for the studied OVOCs + Oxidant at room temperature, (iii) identification and quantification of the gas-phase products, (iv) determination of the SOA yields. The product studies were investigated both with and without adding an OH radical scavenger. Experiments were performed in eight different static (chambers) or dynamic (flow) reactors, and various analytical techniques were used to investigate the reaction products (FTIR, GC-FID/MS, SPME-GC/MS, HPLC, PTR-ToF-MS, SIFT-MS, PLP-LIF) and SOA formation (SMPS, FMPS)

Les composés organiques carbonylés et les BTEX (Benzène, Toluène, Éthylbenzène et Xylènes) représentent une classe importante de composés organiques volatils dans l’atmosphère. Ils sont émis par des sources anthropogénique et biogéniques. Leur dégradation atmosphérique conduit à la formation d’ozone, de phooxidants et d’aérosols organiques affectant ainsi la qualité de l’air aux échelles locales et régionales ainsi que la santé humaine. Il est donc important de mesurer leurs concentrations et évaluer leur devenir atmosphérique. Dans la présente thèse, nous avons conduit une étude systématique qui a permis de mesurer les concentrations de ces composés et identifier leurs sources à Pékin (Juillet 2008-Août 2010) et évaluer l’importance des caractéristiques météo. Nous avons aussi mené des études sur la dégradation atmosphérique de trois formates (isoproyle, isobutyle et n-propyle) en utilisant la chambre de simulation atmosphérique d’ICARE (CNRS, Orléans)
Carbonyls and BTEX (Benzene, Toluene, Ethylbenzene, and Xylenes) represent an important class of VOCs (volatile organic compounds) in the atmosphere. They are emitted into the atmosphere through anthropogenic and biogenic sources. Their atmospheric degradation leads to the formation of ozone, photooxidants and organic aerosols affecting the air quality at the local and regional scales and human health. It is, hence, of importance to measure their atmospheric concentrations and investigate their fate. In the present thesis, we have conducted a systematic measurement study of carbonyls and BTEX in Beijing during the period of Jul 2008-Aug 2010 in order to evaluate their ambient levels, possible sources and the influence of characteristic weather conditions. In a separate work, we performed a series of experimental studies on the OH-initiated oxidation of isopropyl formate, isobutyl formate, and n-propyl isobutyrate using the ICARE-CNRS (Orleans) simulation chamber from which we derived the product yields. The data obtained are presented and discussed

Master of Science
Department of Chemistry
Kenneth Klabunde
Remediation of the indoor environment led to the development of novel catalysts which can absorb light in the visible range. These catalysts were prepared using the wet chemistry method known as sol-gel chemistry because preparation via sol-gel provides a homogeneous gel formation, which can be treated via supercritical drying to produce an aerogel. These aerogels have been found to have high surface areas when a combination of titania/silica is used. The increase in surface area has been shown to enhance the activity of the catalysts. Mixed metal oxide systems were prepared using titanium isopropoxide and tetraethyl orthosilicate to yield a 1:1 system of titania/silica (TiO2/SiO2). These systems were doped during the initial synthesis with transition metals (Mn or Co) to create mixed metal oxide systems which absorb light in the visible light range. These materials were assessed for potential as heterogeneous catalysts via gas-solid phase reactions with acetaldehyde. Degradation of acetaldehyde as well as the formation of CO2 was monitored via gas chromatography-mass spectrometery. To increase the activity, visible light was introduced to the system. Experiments have shown that a 10 mol % manganese doped titania/silica system, in the presence of light, can degrade acetaldehyde. The cobalt doped counterpart showed dark activity in the presence of acetaldehyde resulting in the formation of CO2 without the addition of visible light. In the hope of increasing surface area a mixed solvent (toluene/methanol) synthesis procedure was applied to the manganese doped catalyst. The resulting materials were of a low surface area but showed a significant increase in degradation of acetaldehyde. Examination of the interactions between mixed metal oxide systems and semivolatile organic compounds (SVOCs) was studied. The pollutant, triphenyl phosphate, was dissolved in n-pentane and exposed to 10 mg of a given catalyst. These reactions were monitored using UVVis. All systems but the manganese doped titania/silica system resulted in the observation of no activity with triphenyl phosphate. The manganese doped catalyst shown a peculiar activity, the increase in absorbance of the triphenyl phosphate peaks as well as the formation of a new peak.

Cette thèse porte sur l'étude de dégradation atmosphérique de quelques composés organiques volatils oxygénés par les principaux oxydants atmosphériques OH, Cl, et NO3. Ce travail, comporte, d'une part la détermination des spectres d'absorption UV-Visible des composés hydroxycarbonylés (Hydroxyacétone (HAC), 4-hydroxy-2-butanone (4HB), 3-hydroxy-2-butanone (3HB) et 3-methyl-3-hydoxy-2-butanone (3H3M2B) et d'autre part les mesures cinétiques de la réaction du composé HAC avec le chlore atomique et le radical nitrate. Les réactions entre 4HB et 3H2B avec les radicaux OH et le chlore atomique ont aussi été étudié. Les mesures d'absorption ont été réalisées dans la gamme de température 250 et 363 K à l'aide d'une lampe D2 couplé à un monochromateur. Les valeurs de section obtenues sont utilisées pour calculer la constante de photolyse et d'estimer les durées de vie dans la troposphère des composés étudiés. Les résultats suggèrent que la photolyse pourrait être un processus important pour ces espèces dans la troposphère. Les résultats des études cinétiques, montrent une légère variation des constantes de vitesse avec la température. Nous avons aussi étudié les composés dicétones : 2,4-pentanedione et 2,3-pentanedione. Cette étude porte sur la détermination des spectres d'absorption UV-Visible des composés dicétones et l'étude cinétique de leur réaction avec les radicaux OH en fonction de température. Pour les deux composés une variation de température de plus de 60 % est observée. Les calculs théoriques ont été effectués avec deux programmes différents. Avec logiciel Gaussian 03 nous avons réalisé une optimisation de la géométrie des minima, complexes et états de transition au niveau B3LYP/6-311G++(2d, pd). La méthode composite de haut niveau CBS-QB3 a été utilisée. Et avec le logiciel ChemRate pour les calculs cinétique, et la détermination des constantes de vitesse en phase gazeuse de la réaction étudié en fonction de la température. Les calculs des niveaux d'énergies montrent l'existence d'une étape réactionnelle où il se produit d'un complexe intermédiaire suivi d'une abstraction d'un atome d'hydrogène
This thesis focuses on the study of atmospheric degradation of some Oxygenated Volatile Organic Compounds by major atmospheric oxidants OH, Cl, and NO3. This work comprises firstly determining the spectra of UV-Visible absorption hydroxycarbonyl compounds (hydroxyacetone (HAC), 4-hydroxy-2-butanone (4HB), 3-hydroxy-2-butanone (3HB) and 3-methyl-3-hydoxy-2-butanone (3H3M2B) and secondly measures the kinetics of the reaction of the compound HAC with the atomic chlorine and nitrate radical.Reactions between 4HB and 3H2B with OH radicals and atomic chlorine were also studied.The UV absorption cross-sections of hydroxyacetone, 3-hydroxy 2-butanone, 4-hydroxy 2-butanone and 3-hydroxy 3-methyl 2-butanone have been measured. The experiments have been carried out between 250 and 363 K using a D2 lamp coupled to a monochromator. This work provides the first UV cross-section measurements for 3-hydroxy 2-butanone, 4-hydroxy 2-butanone and 3-hydroxy 3-methyl 2-butanone. The obtained cross-section values are used to calculate the photolysis rates and to estimate the tropospheric lifetimes of the studied compounds. The results suggest that photolysis could be an important removal process for these species in the troposphere. The results of kinetic studies show a slight variation of the rate constants with temperature.We also studied the diketones compounds: 2,4-pentanedione and 2,3-pentanedione. This study focuses on the determination of UV-Visible absorption spectra of diketones compounds and kinetic study of their reaction with OH radicals according to temperature. For both compounds a temperature variation of more than 60% is observed.The theoretical calculations were performed with two different programs: With Gaussian 03 software we performed a geometry optimization minima complex and transition states at B3LYP/6-311G + + level (2d, pd). The high-level composite method CBS-QB3 was used. And with the software ChemRate for kinetic calculations and the determination of rate constants for gas phase reaction according to the studied temperature. Calculations of energy levels show the existence of a reaction step where there is an intermediate complex followed by abstraction of a hydrogen atom

L’oxydation photocatalytique des Composés Organiques Volatils (COVs) apparaît comme un procédé très prometteur pour la réduction de la pollution atmosphérique. Ce travail avait pour objectif d’étudier l’oxydation photocatalytique de plusieurs COVs au sein d’un réacteur annulaire: méthyléthylcétone (MEK), acétone, 1-propanol ou encore triéthylamine (TEA). Dans une première partie, l’influence de plusieurs paramètres cinétiques tels que la concentration en polluant, l’intensité lumineuse, le temps de contact et le taux d’humidité a été étudiée. Un mécanisme de dégradation photocatalytique a été établi pour chaque polluant en fonction des sous-produits détectés par GC/MS. Dans une seconde partie, la diffusion de radicaux hydroxyles OH• dans la phase gazeuse, après activation photonique du TiO2, a été mise en évidence par Fluorescence Induite par Laser (LIF). Pour la première fois, ces radicaux OH• ont été détectés à des pressions proches des conditions atmosphériques. Dans ce cas, nous pouvons en conclure que la dégradation photocatalytique des COVs pourrait être partiellement due à une réaction en phase gazeuse entre les COVs et les radicaux OH•
Photocatalytic oxidation of airborne contaminants appears to be a promising process for remediation of air polluted by Volatile Organic Compounds (VOCs). The aim of our study is the photocatalytic oxidation of several VOCs using an annular reactor: methylethylketone (MEK), acetone, 1-propanol and triethylamine (TEA). First, the influence of different kinetic parameters such as pollutant concentration, incident light irradiance, contact time and humidity has been studied. A mechanistic pathway has been indeed proposed for each pollutant according to the produced intermediates species detected by GC/MS. Second, the diffusion of hydroxyls radicals OH• in gas phase, after photonic activation of TiO2, has been highlighted using Laser-Induced Fluorescence (LIF). For the first time, OH• radicals have been detected at atmospheric pressures, close to the major photocatalytic oxidation conditions, leading to the assumption that the photocatalytic degradation of VOCs might be at least partially occurs between pollutants and OH• radicals in gas-phase

A variety of methods exist to remove volatile organic compound (VOC) air pollutants from contaminated gas streams. As regulatory and public opinion pressures increase, companies are searching for more effective methods to control these emissions. This document is intended as a guide to help determine if existing systems are adequate and to provide additional information to improve the efficiency of the systems. It explores conventional methods of controlling VOC emissions, as well as innovative technologies including membrane separation, plasma destruction, and ozone catalytic oxidation. The conventional technologies covered include condensation, adsorption, absorption (or scrubbing), thermal incineration, flaring, catalytic incineration, and biofiltration. Each chapter includes a description of the technology, a discussion of the types of systems available, notes on the design of the system, economic estimates, an explanation of potential problems, and a list of considerations for installation and maintenance concerns. The final chapter is dedicated to the preparation and characterization of metal catalysts which were developed to improve the reaction rate of VOCs using ozone as an oxidant.
Ph. D.

Indoor air pollution by a variety of volatile organic compounds (VOCs) has become increasingly recognised as a public health problem. Although much work has been done in Scandinavian countries and the United States, very limited studies on the emissions of total VOCs from indoor materials have been reported in countries with Mediterranean climates, or warm temperate climates where the weather conditions and house ventilation rate are quite different from those in which most studies have been reported. There is also a lack of information about specific materials suitable for buildings for which the main priority is healthy indoor air. Therefore, the primary purposes of this project were to characterise VOCs emissions from building materials and consumer products and to develop a model for a low VOC emission house. Environmental test chambers with controlled temperature, relative humidity and air exchange rate were developed to evaluate emissions of total volatile organic compounds (TVOCs) from a variety of building and furnishing materials and consumer products. Organic vapours were collected on Tenax - GR and quantified by GC/FID with thermal desorption techniques. Headspace analysis was used to assess VOCs emitted from indoor pollution sources. The main VOCs were detected by GC/MS techniques. A case study involving the design and development of a low VOCs emission house and testing of this house is presented. This low VOCs emission house emphasises pollution prevention based on the results of environmental chamber testing and headspace analysis. The findings in this study support the hypothesis that indoor materials make significant contributions to the levels of TVOCs in indoor air in houses. This study supports the hypothesis that TVOCs concentrations in indoor air in the houses tested were much lower than those reported in most studies. The findings from this research support the hypothesis that the indoor air quality model is adequate to estimate the TVOCs concentrations in indoor air. Measurements of VOCs emissions from 15 paints, 3 adhesives, 3 furniture polishes, 11 carpets, 6 pressed wood products and 10 consumer products in environmental chambers by GC/FID showed that the indoor materials tested all emitted a variety of VOCs. “Wet” sources such as paints, adhesives, furniture polishes and consumer products, showed a rapid change in initial emission characteristics. These “wet” sources initially have high TVOCs emissions and the concentrations of TVOCs emitted from these materials decreased significantly over time. Most of these “wet” sources emit aromatic hydrocarbons e.g. benzene, toluene, xylene isomers, styrene, ethylbenzene, which are suspected to be carcinogens. “Dry” sources such as carpets and pressed wood products have emission characteristics which change relatively slowly with time. Compared with “wet” sources, these “dry” sources have low TVOCs emissions both in number and amounts of VOCs. Double-exponential empirical models were used to describe the time dependence of TVOCs concentrations and emission rates in environmental chambers. The correlations between measurements of indoor materials in environmental chambers and the predictions of the model showed that the change of TVOCs concentrations for a variety of indoor materials in environmental chambers fitted the double-exponential model very well. The models enabled the characterisation of complex TVOCs emissions and their time dependence with relatively few parameters. With this double-exponential model, the mechanism of TVOCs emissions from indoor materials and products can be characterised. The model also enabled the calculation of a variety of emission parameters which can be used to predict indoor air quality. This study measured TVOCs concentrations in one new conventional house and one low VOCs emission house. The TVOCs concentrations in the conventional house ranged from 60 - 162 Jig/nr and the TVOCs levels in the low VOCs emission house ranged from below the limits of detection (1 jig/m3) to 43 pg/m3. These values are much lower than the published data (0.48-31.7 mg/m3) for new houses. They are even lower than published data for mixed new and old houses (0.19-9.4 mg/m3). This is due to the high air exchange rates in these houses in warm climates, which make maximum use of sea breezes to minimise the accumulation of indoor air pollutants; and the use of low TVOCs emission materials in the low VOCs emission house. An indoor air quality model was used to predict the indoor air quality in these houses. This study preliminarily validates the indoor air quality model by comparing the model predictions with the measured data. This model considered the effects of air exchange rate, source strength and source size on the TVOCs concentration indoors. The correlations (R2 = 0.90, ProbN = 0 - 0.6%) between measurements of indoor TVOCs concentrations in the conventional house (chapter 11) and the predictions of the model showed that the indoor air quality model provided useful predictions of the change of TVOCs concentrations in the conventional house. With this indoor air quality model, the TVOCs concentrations in indoor air under specific conditions (specific ventilation rates and material loadings) can be predicted. This study measured TVOCs rather than individual VOCs concentrations from indoor materials. The next step in research should be aimed at investigating individual VOCs emissions and their effects on indoor air quality and human health. This would extend the existing database to describe and predict emissions of VOCs from indoor materials. It would also provide a better understanding of population indoor exposure.

Aerosols are either emitted directly into the atmosphere or are generated in the atmosphere; the latter process forms secondary organic aerosol (SOA). One of the important sources for SOA is the oxidation of volatile organic compounds (VOCs) by OH radicals, NOx, and O3. Aerosol can be visualized as suspended solid or liquid particle which is in equilibrium with surrounding gases. The products of SOA formation is a mixture of semi volatile organic compounds and a fraction of the products are condensable under atmospheric conditions. The condensable portion of aerosol is called particulate matter (PM) and these suspended particles can range in diameter from a few nanometers to microns. PM can impact climate through direct and indirect radiative forcing and can degrade air quality by reducing visibility and causing detrimental health effects. SOA can also form indoors, which also contributes to the health risk of PM. The severe impact of PM on human health and climate drives the scientific community to investigate the volatile organic compounds (VOCs) and their potential to form SOA, as well as the factors that alter the efficiency of SOA generation and the type of products. In a similar pursuit, the focus of this dissertation is the investigation of the SOA precursors that are emitted from trees and how they vary as a function of insect infestation. Also, the role of mixtures of VOCs as SOA precursors are investigated; commercial and lab made VOC mixtures are studied for SOA generation, product analysis, and absorption characteristics of aged SOA. Chapter 1 introduces PM, VOCs present in atmosphere, SOA generation, and speciation of products generated from the ozonolysis of VOCs. The impact of PM on human health and climate are summarized. A literature survey on the VOCs that are precursors to SOA and present in the outdoor and indoor environment is presented along with factors that may lead to variability in amount of VOCs. SOA generation from direct plant emissions and consumer products is surveyed. These studies show that VOC oxidation generate SOA which is important in the atmosphere due to climate and health effects and indoors due to health effects. A summary of SOA phase partitioning theories, the reaction mechanism for the formation of products from ozonolysis of the dominant biogenic SOA precursors (monoterpenes), and the factors that affect SOA generation is presented. Chapter 2 summarizes the results obtained from a field study assessing the impact of bark beetle infestation on SOA precursor emissions from forests in the Western United States. Samples of VOCs were collected by our collaborators from healthy and bark beetle infested trees using scent traps. We solvent extracted and analyzed by gas chromatography/mass spectrometry (GC/MS) nearly four hundred scent traps. An increase in the total and the individual VOCs emitted by infested trees was measured. A statistical analysis shows significant differences between the emissions from infested and healthy trees. A perspective is provided on potential impact of bark beetle infestation on regional SOA. The majority of the laboratory experiments for SOA generation have focused on individual VOCs as the single SOA precursor. However, as demonstrated in Chapter 2 for example, in a real environment multiple VOCs co-exist. Multiple SOA precursors undergo concurrent oxidation reactions, and it is not known if the products from concurrent oxidation of multiple precursors are the same as the sum of the products from individual SOA precursors. Mass closure analysis of field samples show that a significant fraction of the chemical identity of organic PM is unknown, but the chemistry impacts the toxicity of PM. Hence, it is important to understand SOA formation from realistic SOA mixtures. Chapter 3 describes the results of the SOA generation by ozonolysis of limonene and VOC mixtures containing limonene. We use an additive approach for building a surrogate VOC mixture close in composition to a commercially-available mixture. The yield of PM as a function of VOC precursor mixture was measured with respect to VOC composition using smog chamber SOA generation and scanning mobility particle sizing. PM in the chamber was collected onto filters and extracted, and the individual products of SOA were identified and quantified by GC/MS. The condensed-phase SOA products generated during these experiments for different VOC mixtures are compared. In Chapter 4, condensed-phase products sampled from SOA generated by the ozonolysis of α pinene and VOC mixtures containing α pinene, including two fir needle essential oils, are studied by extracting filter samples and analyzing the extracts by GC/MS. The products generated from VOC mixtures are characteristic of the most dominant VOC present in the mixture i.e. either limonene or α pinene. Some mixtures show the generation of new products which are not observed for corresponding individual VOC ozonolysis and hence can be used as marker for the corresponding VOC mixture. The distribution of α-pinene SOA products changes as the composition of the SOA precursor mixture changes. In Chapter 5, the UV visible absorption characteristics of ammonium ion aged SOA are discussed. Ammonium ion aging of aerosol leads impacts the radiative properties of aerosol and has the potential to impact aerosol's role in climate change. Filter samples containing SOA generated from two mixtures with different dominant monoterpenes (α-pinene-based Siberian fir needle oil and a limonene-based air freshener) were extracted. The absorption coefficients of the extracts were measured as a function of ammonium ion aging time using UV-visible absorption spectrometry. The conclusions from all above chapters are summarized in Chapter 6.

The subject of this PhD is the development and testing of a portable membrane inlet mass spectrometer (MIMS), for the in-situ measurement of volatile organic compounds (VOCs) in air. There are several types of VOC monitor available, but few are able to monitor in-situ with near real-time measurements at concentrations around or lower than ppm levels. This PhD focuses on the development of the MS-200 and demonstrates its performance in laboratory and field conditions to analysis a range of VOCs. The first chapters of this thesis describe the design considerations that led to the development of the MS-200. It also discusses the working principles of the instrument and the laboratory based performance tests that compare the performance of the MS-200 with the industry standard VOC monitor. As the MS-200 has sensitivity and detection limits down to ppb levels, it overcame the limitations of many other instruments, and enabled its use for many new applications. For example, aromatic and chlorinated hydrocarbons report detection limits of between 600ppt to 20ppb, other VOCs investigated, reported detection limits between 20 to 300ppb, low molecular weight alcohols report detection limits of 0.4 to 6ppm. However, some applications require even lower detection limits, so an alternative inlet system was developed to increase the sensitivity but at the expense of the near real-time measurement capability. Typically the alternative inlet system reduces detection limits by two orders of magnitudes compared with the standard MS-200. Subsequent sections of this thesis describe and discuss a range of real world applications for the MS-200. Most of these investigations were successful, although a number would need some further work before the MS-200 would be capable to perform such applications routinely in a commercial environment. The applications discussed include: Investigations into arson where the instrument can be used to detect remnants of accelerants used without needing to return samples to the lab, giving the potential to save both time and money; Monitoring personal exposure to benzene when refuelling a petrol car, where the MS-200 demonstrated the advantage of portable real-time monitoring. It was found that during refuelling the operator could be exposed to benzene concentrations of a few hundred ppb to 4ppm for a duration of about 3 minutes; Measuring VOC markers in human breath as a diagnostic tool for cancer and other illnesses; The use of the MS-200 as an "artificial nose" in the food quality and flavour analysis. The thesis discusses the advantages and limitations of this technology as well as providing a series of recommendations for its future development.

It is now recognised that indoor environments contribute significantly to human exposure to airborne pollutants. People spend a large amount of time in indoor environments and there are many indoor sources that are not present outdoors. Among the chemicals released in indoor environments, some of them have been identified as hormonally active or carcinogens. Indoor air pollution problems are likely to become more as stricter controls limit outdoor pollution levels. Reduction of air exchange rate and the use of new insulating materials are likely to contribute to the build-up of pollutants in indoor air. The objective of this thesis has been to develop an analytical method based on thermal desorption for the measurement of semivolatile organic compounds (S'\iO:s) to be use for indoor and personal measurements. The sampler consists of a small FMz.s impactor upstream of a sample tube filled with the adsorbent Tenax TA to collect the particulate 'and gaseous phases respectively. The analytical technique was based on thermal desorption to compensate for the low sampling volumes available with the personal sampling pump so that the entire sample can be injected on the analytical system. In addition, the current technique reduces the analytical time and cost because little sample handling is required and it is more environmental friendly because no solvents are used. The experimental work focused on the development of a vapour generation system to determine breakthrough volumes of the least volatile target compounds on the adsorbent Tenax TA, the development of the analytical method for the analysis of both the gaseous and particulate phases and the evaluation of the performance of the developed method. Finally, the applicability of the method was verified by performing a short stUdy involving indoor and personal samplings. The developed vapour generation system permitted vapours to be generated at concentrations that are representative of indoor air concentrations. The apparatus has been evaluated for a number of SIt is now recognised that indoor environments contribute significantly to human exposure to airborne pollutants. People spend a large amount of time in indoor environments and there are many indoor sources that are not present outdoors. Among the chemicals released in indoor environments, some of them have been identified as hormonally active or carcinogens. Indoor air pollution problems are likely to become more as stricter controls limit outdoor pollution levels. Reduction of air exchange rate and the use of new insulating materials are likely to contribute to the build-up of pollutants in indoor air. The objective of this thesis has been to develop an analytical method based on thermal desorption for the measurement of semivolatile organic compounds (S'\iO:s) to be use for indoor and personal measurements. The sampler consists of a small FMz.s impactor upstream of a sample tube filled with the adsorbent Tenax TA to collect the particulate 'and gaseous phases respectively. The analytical technique was based on thermal desorption to compensate for the low sampling volumes available with the personal sampling pump so that the entire sample can be injected on the analytical system. In addition, the current technique reduces the analytical time and cost because little sample handling is required and it is more environmental friendly because no solvents are used. The experimental work focused on the development of a vapour generation system to determine breakthrough volumes of the least volatile target compounds on the adsorbent Tenax TA, the development of the analytical method for the analysis of both the gaseous and particulate phases and the evaluation of the performance of the developed method. Finally, the applicability of the method was verified by performing a short stUdy involving indoor and personal samplings. The developed vapour generation system permitted vapours to be generated at concentrations that are representative of indoor air concentrations. The apparatus has been evaluated for a number of SVOCs including PAHs, phthalates, organophosphate esters and alkylphenol) with as including FW-Is, phthalates, organophosphate esters and alkylphenol) with a broad range of volatility (from naphthalene to pyrene). The breakthrough measurement study performed in the worst conditions (30 0e and 7CJllo relative humidity) demonstrated that the adsorbent Tenax TA was appropriate to quantitatively collect even the least volatile compound naphthalene over a 24 hours sampling period. The analytical method was developed for 16 R\Hs, 6 CB*is, 5 phthalates, 2 organophosphate esters, 3 alkylphenols and 5 pesticides (2 organophosphorous, 1 carbam~te, 1 pyrethro'id and 1 organochlorine). Its applicability for R\Hs measurements was verified with a standard reference material (SRM1649a, NIS1) and by comparison of indoor air filter strips analysed by the Tn method and a conventional solvent extraction method. The 10 method was shown to be quantifiable for R\Hs up to benzo(a)pyrene but less effective for less volatile At\Hs due to their incomplete desorption. A side by side comparison between the developed sampler and a low volume Filter/PUF sampler clearly demonstrate that the developed method was much more efficient than the low volume PUF sampler for the measurement of gaseous low molecular weight compounds (Mw S178 g.mol-1 ). Regarding the particulate phase, measured concentrations from both samplers were highly correlated with the exceptions of the heavy R\Hs (IP, DahA and BghiP). These results suggest that sampling artifact were limited or similar to those of the low volume sampler. The precision of the method was evaluated by the relative standard deviation from co-located measurements in an indoor environment (n=6). A number of target .compounds were detected including R\Hs, CH\Hs, phthalates, organophosphate esters and phenol. The relative standard deviation was generally less than 1CJllo indicating good reprodUcibility. A small demonstration study consisting of twenty four hours indoor and personal measurements was carried during six days. The results obtained in this demonstration study were in agreement with most previous studies reporting indoor heavy At\Hs concentrations lower or similar than outdoor R\Hs concentrations and light R\Hs concentrations higher indoors than in outdoor environments. This demonstration study also confirmed that phthalates and organophosphate esters are ubiquitous in indoor environment.

Rapid, sensitive and selective detection and identification of pathogens is required in the prevention and recognition of problems related to food security. Salmonella is one of the dangerous foodborne pathogens. The identification of specific volatile organic compounds (VOCs) produced by Salmonella may contribute in providing a fast and accurate detection method for Salmonella in food samples. In this study, VOCs liberated by Salmonella strains have been identified and quantified via head space-solid phase microextraction coupled to gas chromatography/mass spectrometry (HS-SPME GC/MS). The dominant chemical class of volatiles liberated from Salmonella strains was alcohol compounds. In addition, ester and ketone compounds were also detected. The most sensitive VOCs detected were ethyl octanoate (LOD = 62.0 ng/mL and LOQ = 207 ng/mL) and ethyl decanoate (LOD = 66 ng/mL and LOQ = 219 ng/mL) with the lowest LOD and LOQ when using Rappaport-Vassiliadis Soya peptone (RVS) broth media and polar SPME fiber with polar GC column. The type of culture medium was found to affect the liberated VOCs. For example, 2-heptanone was not detected when S. london and S. stanley were grown in TSB but they were detected and quantified when using BHI as growth media. Also, 1-octanol was detected and quantified in all strains when Salmonella grown in TSB and BHI, and did not detected in all strains when RVS was used as growth media. The research has been extended to include the addition of specific enzyme substrates to the culture medium (RVS). The enzyme substrates are either commercially available or have been synthesised to allow exogenous VOC detection. The specific enzymes targeted in Salmonella were α-galactosidase, C-8 esterase and pyrrolidonyl peptidase. The enzyme substrates used are phenyl α-D-galactopyranoside, 2-chlorophenyl octanoate and L-pyrrollidonyl fluoroanilide respectively. All, except pyrrolidonyl peptidase, are known to give a positive response to Salmonella. This developed methodology was initially applied to pure cultures of S. stanley to evaluate the feasibility of the approach. The developed approach shows potential for future application in food samples to detect and identify Salmonella species in food samples of a level as low as 100 CFU/mL within a 5 h incubation at 37 ºC by the detection of the liberated VOCs. Subsequently the methodology was applied to a range of food samples (milk, cheese, eggs and chicken). It was found that all food samples were Salmonella free; however, false positive was detected due to the presence of other pathogens in the food samples. Inhibition of some of these pathogens in milk and cheese samples was achieved with the addition of 5 mg/L vancomycin and 10 mg/L of novobiocin. To improve the method specificity, it was necessary to deviate from the standard method and use Salmonella selective RVS broth in pre-enrichment step than using non selective one (BPW). This results in a successful detection of Salmonella contamination on milk samples and cheddar cheese samples. However, failed in detect Salmonella in other cheeses. Inhibition of resistant pathogens (Streptococcus salivarius ssp. Thermophilus, Lactobacillus rhamnosus and Enterococcus faecalis) using another combination of selective agents (vancomycin 10 mg/L, novobiocin 10 mg/L, erythromycin 0.75 mg/L and lithium chloride 15 g/L) failed. This study highlighted the benefits of the use of specific enzyme substrates along with antibiotics into Salmonella VOC analysis to improve the specificity of Salmonella detection method. The results of VOC analysis of specific enzymes inherent within Salmonella could be extended to develop a selective portable sensor approach to be used in food production.

A non-invasive, inflammatory bowel disease (IBD)-specific biomarker would be clinically useful due to the often inaccurate and unpleasant current diagnostic methods. The duration and extent of IBD increases the risk for colorectal cancer (CRC) therefore non-invasive screening for CRC in patients with long-term IBD may lead to early detection of abnormal changes and improve the chance of survival. To date, human metabolomic studies have shown potential for the identification of a faecal marker of IBD, but are limited by variation from diet, environment and medication. The aim of this work was to report the first study using HS-SPME-GC- MS to detect the VOC faecal metabolome in commonly used mouse models of IBD and CRC. Using an optimized method, the identification of the healthy murine faecal VOC profile resulted in little variation between individual mice with a noted significant effect of gender and age. Comparison of healthy mouse to human found 39 and 62 VOCs respectively with 33% overlap between the two species, thereby demonstrating the more complex gut environment of humans. These studies led to the identification of a VOC profile, characterized by an increase in aldehydes and a decrease in alcohols, as a marker of acute diarrhoea, compared to a significantly different profile for chronic colitis, characterised by the presence of methyl ketones. In addition, VOC profiling is capable of detecting murine-specific metabolic signatures associated with premalignant lesions of the colon, providing rationale for the investigation of new non-invasive methods for early tumour detection. These results were supported by findings questioning the specificity of faecal calproctectin as a marker of IBD due to the increased levels of calprotectin found in both colitis and cancer groups, compared to healthy controls. In conclusion, we have provided evidence that the identification of disease-associated VOC concentration ranges combined with specific marker compounds would potentially increase the likelihood of finding an IBD-specific faecal VOC marker profile. This work has presented rationale for future studies to investigate further the true origin of these marker VOCs by performing both in vitro and further in vivo work. The investigation of the faecal metabolome of a number of different murine models in combination, rather than the use of a single mechanistic model may be provide a better reflection of human disease.

The maintenance or replacement of deteriorated pipes and culverts is a constant and significant concern for municipalities and transportation agencies in the United States (Donaldson and Wallingford, 2010). Trenchless technologies and especially the Cured-in-place pipe (CIPP) method have become increasingly common ways to preserve infrastructures owing to their feasibility, cost-effectiveness, and fewer social impacts (Jung and Sinha, 2007). Therefore, there is a growing need to understand the direct and indirect effects of pipeline rehabilitation activities on the environment. Nearly all past CIPP studies have focused on its mechanical properties, and its environmental impacts are poorly investigated and documented (Allouche et al. 2012). Sewer pipelines and storm-water culverts are administered by municipalities and transportation agencies who bear the responsibility for rehabilitation and renewal of these infrastructures. In consequence, they rarely allow sampling and research projects in the field due to liability issues. This is a main obstacle to conducting comprehensive, precise, and unbiased research on CIPP environmental impacts and to date, the degree of relevant health effects and related environmental impacts have remained unknown. Numerous building indoor air contamination incidents indicate that work is needed to understand the magnitude of styrene emission from CIPP sanitary sewer repairs. The main goal of this study was to better comprehend Volatile Organic Compounds emission at three CIPP sanitary sewer installation sites in one U.S. city. Results showed that CIPP chemical emissions may be a health risk to workers and nearby building inhabitants. Additional testing and investigations regarding chemical emissions from CIPP should be commissioned to fill in the environmental and public health knowledge gaps. The acute and chronic chemical exposure risks of CIPP chemical steam constituents and styrene to sensitive populations should be further examined. Other goals of this study were to estimate the magnitude of solid waste generated as well as the amount of certain criteria air pollutants and greenhouse gases emitted from onsite heavy equipment for both CIPP and open-cut sites in a U.S city. The results indicated that the amount of open-cut related solid waste, criteria air pollutants, and greenhouse gases were greater than those during CIPP activities. Additional work is needed to quantify pollutant emissions from CIPP and open-cut activities and consider emissions from a cradle-to-grave standpoint.

The maintenance or replacement of deteriorated pipes and culverts is a constant and significant concern for municipalities and transportation agencies in the United States (Donaldson and Wallingford, 2010). Trenchless technologies and especially the Curedin- place pipe (CIPP) method have become increasingly common ways to preserve infrastructures owing to their feasibility, cost-effectiveness, and fewer social impacts (Jung and Sinha, 2007). Therefore, there is a growing need to understand the direct and indirect effects of pipeline rehabilitation activities on the environment. Nearly all past CIPP studies have focused on its mechanical properties, and its environmental impacts are poorly investigated and documented (Allouche et al. 2012). Sewer pipelines and storm-water culverts are administered by municipalities and transportation agencies who bear the responsibility for rehabilitation and renewal of these infrastructures. In consequence, they rarely allow sampling and research projects in the field due to liability issues. This is a main obstacle to conducting comprehensive, precise, and unbiased research on CIPP environmental impacts and to date, the degree of relevant health effects and related environmental impacts have remained unknown.

Numerous building indoor air contamination incidents indicate that work is needed to understand the magnitude of styrene emission from CIPP sanitary sewer repairs. The main goal of this study was to better comprehend Volatile Organic Compounds emission at three CIPP sanitary sewer installation sites in one U.S. city. Results showed that CIPP chemical emissions may be a health risk to workers and nearby building inhabitants. Additional testing and investigations regarding chemical emissions from CIPP should be commissioned to fill in the environmental and public health knowledge gaps. The acute and chronic chemical exposure risks of CIPP chemical steam constituents and styrene to sensitive populations should be further examined.

Corpus Christi among of the largest industrialized coastal urban areas in Texas. The strategic location of the city along the Gulf of Mexico allows for many important industries and an international business to be located. The cluster of industries and businesses in the region contribute to the air pollution from emissions that are harmful to the environment and to the people living in and visiting the area. Volatile organic compounds (VOC) constitute an important class of pollutants measured in the area. The automated gas chromatography (Auto GC) data was collected from Texas Commission of Environmental Quality (TCEQ) and source apportionment analysis was conducted on this data to identify key sources of VOC affecting this study region. EPA PMF 3.0 was employed in this sources apportionment study of measured VOC concentration during 2005 - 2012 in Corpus Christi, Texas. The study identified nine optimal factors (Source) that could explain the concentration of VOC at two urbane monitoring sites in the study region. Natural gas was found to be the largest contributor of VOC in the area, followed by gasoline and vehicular exhaust. Diesel was the third highest contributor with emissions from manufacturing and combustion processes. Refineries gases and evaporative fugitive emissions were other major contributors in the area; Flaring operations, solvents, and petrochemicals also impacted the measured VOC in the urban area. It was noted that he measured VOC concentrations were significantly influenced by the economic downturn in the region and this was highlighted in the annual trends of the apportioned VOC.

In recent years, consumers have become increasingly interested in the quality aspects of food. Food quality, in turn, is strongly related to the sensory characteristics such as the flavor. Several scientific studies have shown that the Volatile Organic Compounds (VOCs) released by the food are related to the flavor and can be considered as assistive markers in the production chain. Today, the analysis of VOCs requires fast, non-invasive, and solvent free devices. It has been shown that the VOCs can be extracted, identified, and measured with a Gas Chromatography-Mass Spectrometry (GC-MS) without any pre-concentration or pre-treatment of the food. The main objective of this PhD thesis was to investigate the presence of volatile compounds in dairy products. More precisely, this study aimed in i) qualifying and quantifying VOCs in dairy products, ii) examining their formation and iii) integrating knowledge on VOCs by tracking their release during the whole production process from the raw materials till the final dairy product. In addition, statistical analysis was applied to link VOCs with the genetic characterization of animals, dairy system and individual cow-factors (e.g. stage of lactation, order of parity and milk yield). The identification and quantification of VOCs were performed using fast and non-invasive analytical approaches (Solid Phase Micro Extraction/Gas Chromatography-Mass Spectrometry SPME/GC-MS and Proton Transfer Reaction-Time of Flight-Mass Spectrometry PTR-ToF-MS) that can monitor the evolution of VOCs. To achieve the overall goal, the research was partitioned in four interrelated subparts as described below. The aim of the first chapter was to study the VOCs presence in the headspace of cheese. To this purpose, 150 cheeses ripened for two months were used. The cheeses were obtained through an individual model cheese-making approach using milk from individual Brown Swiss cows. Animals reared in 30 herds belonging to different dairy systems, from traditional (typical of the mountainous area) to modern ones. The study identified 55 VOCs classified in the chemical families of free fatty acids, esters, alcohols, aldehydes, ketones, lactones, terpenes, and pyrazines. We found that dairy system and individual cow characteristics (lactation stage, order of parity and daily milk yield) influenced the volatile compounds. In order, to test the instrument reproducibility and the model cheese-making procedure; data of GC analysis, order of injection of the sample into instrument, and vat were included in the statistical model. In many cases, these analytical factors did not affect the amount of VOCs released by cheese. In the second chapter, the potential of a new spectrometric technique (PTR-ToF-MS) was investigated to study cheese quality traits on a large scale. The PTR-ToF-MS allows direct injection of the sample headspace without extraction or pre-concentration steps, has a shorter analysis time (only a few seconds per sample) and greater sensitivity that permit to monitor on-line the evolution of volatile compounds. The resulting spectral information can provide a very detailed description of samples, which is useful for characterizing food quality and typicality. In particular, we analyzed the volatile fingerprint of 1,075 model cheeses produced using individual milk of Brown Swiss cows reared in 72 herds of different dairy systems. The output of PTR (spectrum) was characterized by more than 600 spectrometric peaks (variables). After removing interfering ions and background noise a set of 240 peaks was selected. Further, based on the results of the first contribution and literature, 61 peaks were identified. These peaks represent the major part of the cheese flavor. To summarize the amount of information, a multivariate analysis (PCA) was applied associating principal components (PC) with the 240 spectrometric peaks. Following, we tried to characterize the PCs through the correlations between PCs and the spectrometric peaks. The effects of dairy system, herd within dairy system, individual cows characteristics (lactation stage, order of parity and milk yield), and vat used for the cheese-making on the PCs and on the 240 peaks were analyzed. Dairy system was correlated with PC and 57 spectrometric peaks, especially when the herds were using Total Mixer Ration (TMR) as feeding technique, including or not maize silage in the diets. Regarding the individual animal characteristics, the most significant effect was the stage of lactation (139 peaks), followed by milk yield and parity, with 31 and 21 peaks, respectively. Finally, the vat used for the cheese-making was not found to be significant, confirming the good reproducibility of the model cheese-making procedure used to study cheese quality aspects. In the third chapter, the effect of cows’ genetics to the VOCs of ripened cheeses was assessed. Principal components and the 240 spectrometric peaks (as described above in the second contribution) were used fitting an animal model in a Bayesian framework. On average, heritability (h2) of 7% for PCs was found, which is similar to h2 of somatic cell count and much lower than the h2 of milk fat content and daily milk yield. It is interesting to note that only a small proportion of peaks showed very low h2 (<7%). The major part of them showed values similar to those found for PCs, while forty peaks presented heritability similar to that of milk yield and other milk quality traits. The variability attributed to the herd was different for the various PC. Results suggest a potential of improvement for several cheese VOCs through genetic selection in dairy cow breeding programs. The aim of the fourth chapter was to study the effect of summer transhumance on the quality traits of dairy products. Due to the extended work, this contribution was further splitted into two parts. In the first part, the evolution of milk and cheese quality characteristics were studied, while in the second part the evolution of VOC content of dairy products was analyzed. For the first part, chemical characteristics and technological properties of 11 dairy products obtained during summer transhumance of cows to Alpine pastures (Malga) were analyzed. Dairy products obtained throughout this period are known to give origin to high-value, healthier products, and extra tasty,. Bulk milk from 148 dairy cows reared day and night on Alpine pasture (1,860 m a.s.l.) was used. We performed 7 experimental cheese-making according to traditional mountain techniques, one every two weeks, using milk produced during the summer transhumance (from June to September). For each cheese-making we collected: milk from the evening milking (day before the cheese-making), the same milk the following morning (after natural creaming), the cream separated, the whole milk from the morning milking, the milk in vat obtained mixing the creamed evening milk with the whole morning milk, the fresh curd, the whey, the ricotta obtained from whey, and the residual scotta. Moreover, the curd was used to produce typical “Malga” cheese that was ripened for 6 and 12 months. The chemical characteristics were measured with infrared technology. Results highlighted variation in milk yield, milk chemical composition, cheese yield and curd recoveries and/or loss of nutrients in the traditional cheese-making. In particular, a reduction of milk yield, fat, protein and lactose contents of milk during summer transhumance was observed. Nevertheless, the return to lowland farming systems of the cows at the end of grazing season, positively affected milk yield and milk chemical composition. The average of cheese yield was 14.2%, while recoveries of fat, protein, total solids and energy were 85.1%, 77.8%, 49.4% and 58.1%, respectively. These results were in accordance to those found in the literature. For the second part of this chapter, the VOCs content of sample headspace was measured through SPME/GC-MS. Forth nine VOCs belonging to the chemical families of alcohols, aldehydes, free fatty acids, ketones, esters, lactones, terpenes, phenolic, and sulphur compounds were detected. In addition, the evolution of VOCs and their chemical family across the cheese- and ricotta-making processing as well as during the cheese ripening period was tracked. The comparison between VOCs concentration of 4 types of milk (whole evening, creaming milk, whole morning, milk in vat) showed that the creaming process significantly affected about half of all the volatile organic compounds analyzed, followed by the effects of milking (evening milking vs. morning milking) and the mixing (creamed milk mixed with whole morning milk). In general, the cream, in contrast to curd and ricotta, showed higher content of free fatty acids, sulphurs and terpenes compounds. Moreover, in ricotta a higher VOC concentration was observed compared to the curd, probably due to the high temperature required during the ricotta process. The effect of the progressive nutrient depletion of milk was investigated by contrasts between VOC concentration of milk in the vat, whey, and scotta. Although milk contains a greater amount of nutrients, whey and scotta have shown a higher concentration of VOCs with the exceptions of esters, sulphurs, terpenes and phenolic compounds. Finally, the effect of ripening was tested by comparing the quantity of VOCs of curd and of aged cheeses (6 and 12 months). The release of volatile compounds increased with increasing ripening period in relation with the enzymatic and microbiological activity of cheese. In summary, the spectrometric techniques (SPME/GC-MS and PTR-ToF-MS) used in this work demonstrated to be very efficient to characterize the volatile organic compounds of dairy products. The dairy system, and cow related factors affected the volatile fingerprint of ripened cheeses. Particularly, concerning the individual animal source of variation, lactation stage was the most important effect followed by the cow’s parity and the milk yield. On the basis of phenotypes used in this work, the traits collected offered the potential for a genetic analysis to be carried out. The genetic analysis demonstrated the existence of an exploitable genetic variability of the volatile profile of cheese that might be useful for an (in)direct selection of dairy cows for cheese quality traits in breeding programs. Nevertheless, further research is needed in this area. In the era of genomics for e.g., it might be interesting to associate genomic regions to specific VOCs. This information might be useful for genomic breeding programs. The evolution of volatile compounds across the production chain depends on specific technological aspects, such as the process of natural creaming, the temperature of coagulation, and the ripening period. The monitoring of volatile fingerprint permits to obtain dairy products with specific organoleptic characteristics useful to differentiate them on the market and to improve the supply chain efficiency on the basis of quality aspects.
Negli ultimi anni, il consumatore è diventato sempre più sensibile agli aspetti qualitativi degli alimenti, i quali sono fortemente influenzati dalle caratteristiche sensoriali come l’aroma. Diversi lavori scientifici hanno dimostrato che i composti volatili (VOCs) rilasciati dall’alimento sono correlati con il suo aroma e possono essere considerati come traccianti delle filiere alimentari. Oggi, l’analisi dei VOCs richiede strumenti rapidi, sensibili, non invasivi e che abbiano bisogno dell’impiego di pochi solventi durante la preparazione del campione. E’ stato dimostrato che i VOCs possono essere estratti, misurati e identificati con la Gas Cromatografia di Massa (GC-MS) senza pre-concentrazioni o pre-trattamenti dell’alimento da analizzare. Gli obiettivi principali della tesi di dottorato erano di studiare la presenza di composti volatili nei prodotti lattiero-caseari. Più precisamente, questo studio aveva come obiettivi di i) qualificare e quantificare i VOCs nei prodotti lattiero-caseari, ii) esaminare la loro formazione e iii) integrare le conoscenze acquisite su questi composti attraverso tutta la filiera di produzione dalla materia prima fino al prodotto finito. Inoltre, analisi statistiche sono state utilizzate per collegare i VOCs con la caratterizzazione genetica degli animali, il sistema di allevamento e le caratteristiche individuali delle vacche (es. stadio di lattazione, ordine di parto e produzione giornaliera di latte). L’identificazione e la quantificazione dei VOCs sono state fatte utilizzando tecniche analitiche precise, veloci e non invasive (Solid Phase Micro Extraction/Gas Chromatography-Mass Spectrometry SPME/GC-MS and Proton Transfer Reaction-Time of Flight-Mass Spectrometry PTR-ToF-MS). Per rispondere agli obiettivi generali della tesi, l’attività di ricerca è stata divisa in cinque parti connesse tra di loro. L’obiettivo nel primo capitolo era di studiare i composti volatili presenti nello spazio di testa di campioni di formaggio. Per questo scopo, sono stati analizzati 150 formaggi stagionati per due mesi. I formaggi sono stati prodotti utilizzando una metodica di caseificazione individuale usando latte individuale di vacche di razza Bruna. Gli animali sono stati allevati in 30 aziende appartenenti a diversi sistemi di allevamento, da tradizionale (tipico della realtà montana) a moderno. In questo studio sono stati identificati 55 VOCs per ogni formaggio, classificati in diverse famiglie chimiche: acidi grassi, esteri, alcoli, aldeidi, chetoni, lattoni, terpeni e pirazine. Dai risultati emerge che il sistema di allevamento e le caratteristiche individuali delle vacche (stadio di lattazione, ordine di parto e produzione giornaliera di latte) influenzano i composti volatili. Inoltre, per testare la riproducibilità dello strumento e della metodica di caseificazione; la data di analisi cromatografica, l’ordine d’iniezione del campione nello strumento (GC), e la caldaia di caseificazione erano inclusi nel modello statistico. In molti casi, questi fattori analitici/strumentali non influenzano la quantità di VOCs rilasciata dai formaggi. Nel secondo capitolo, il potenziale di una nuova tecnica analitica (PTR-ToF-MS) è stato approfondito per studiare, su larga scala, le caratteristiche qualitative del formaggio. Il PTR-ToF-MS dal punto di vista analitico, permette un’iniezione diretta del campione senza estrazione o pre-concentrazione, ha un breve tempo di analisi (solo pochi secondi per campione) e grande sensibilità consentendo di monitorare in tempo reale l’evoluzione dei composti volatili. L’analisi produce uno spettro molto dettagliato che può essere utile per la caratterizzazione delle qualità e della tipicità dell’alimento. In particolare, è stata analizzata l’impronta aromatica di 1,075 formaggi prodotti utilizzando latte individuale di vacche di razza Bruna allevate in 72 aziende appartenenti a diversi sistemi di allevamento. L’impronta aromatica (spettro) era caratterizzata da più di 600 picchi (variabili) per ogni formaggio. Gli spettri sono stati analizzati e dopo la rimozione degli ioni interferenti e del rumore di fondo è stato selezionato un data set costituito da 240 picchi per ogni formaggio. In seguito, basandosi sui risultati del primo contributo e sulla letteratura sono stati identificati i picchi più importanti (61) in termini quantitativi e qualitativi. Per sintetizzare la quantità di informazioni ovvero estrarre delle componenti principali (PC) è stata fatta un’analisi multivariata (PCA) a partire dai 240 picchi spettrometrici. In seguito, le PCs sono state caratterizzate sulla base delle loro correlazioni con i 240 picchi spettrometrici. Sono stati analizzati gli effetti del sistema di allevamento, dell’azienda entro sistema di allevamento, le caratteristiche individuali delle vacche (stadio di lattazione, ordine di parto e produzione di latte), e caldaia di caseificazione sulle PCs e sui 240 picchi. Dai risultati emerge che il sistema di allevamento è correlato con le PC e 57 picchi, specialmente quando le aziende come tecnica di alimentazione utilizzano il carro miscelatore (TMR) con e senza insilati nella dieta. Considerando le caratteristiche individuali delle vacche, l’effetto più significativo è lo stadio di lattazione (139 picchi), seguito dalla produzione di latte e dall’ordine di parto, con 31 e 21 picchi, rispettivamente. Infine, la caldaia di caseificazione è un effetto spesso non significativo, confermando la buona riproducibilità della micro-caseificazione utilizzata anche per lo studio di aspetti qualitativi del formaggio. Nel terzo capitolo è stato studiato l’effetto della genetica dell’animale sui composti volatili dei formaggi. A tale scopo, sono state analizzate le componenti principali (estratte come discusso sopra nel secondo contributo) e i 240 picchi spettrometrici (PTR-ToF-MS) utilizzando un modello animale con un approccio Baesiano. Dai risultati emerge in media un’ereditabilità (h2) del 7 % per le componenti principali, la quale è simile all’h2 trovata per le cellule somatiche e leggermente più bassa di quella del contenuto di grasso nel latte e della produzione giornaliera di latte stimate in precedenza sugli stessi animali. E’ interessante osservare che solo una piccola quantità di picchi ha una bassa h2 (<7%). La maggior parte di essi presenta valori simili a quelli trovati per le PCs, mentre 40 picchi presentano ereditabilità simile a quella trovata per la produzione giornaliera di latte e ad altre caratteristiche qualitative del latte. La variabilità attribuita all'azienda è risultata diversa per le PCs. Questi risultati dimostrano che esiste un’interessante variabilità genetica di alcuni VOCs che potrebbe essere potenzialmente utilizzata nei programmi di miglioramento genetico. L’obiettivo nel quarto capitolo era di studiare l’effetto della transumanza sulle caratteristiche qualitative di prodotti lattiero-caseari. Vista la grande mole di dati, questo contributo è stato diviso in due parti tra loro connesse. Nella prima parte è stata studiata l’evoluzione della qualità del latte e del formaggio, mentre nella seconda parte è stata analizzata l’evoluzione dei composti volatili dei prodotti lattiero-caseari nel processo di caseificazione. Nella prima parte, sono state analizzate le proprietà fisiche, chimiche e tecnologiche di 11 prodotti lattiero-caseari raccolti durante la transumanza al pascolo Alpino (Malga) di vacche da latte. E’ risaputo che i prodotti ottenuti durante il periodo di alpeggio possono avere un valore aggiunto dovuto alle elevate proprietà nutrizionali, salutistiche e aromatiche. Per approfondire le conoscenze finora acquisite, è stata fatta questa prova in cui è stato utilizzato il latte di massa prodotto da 148 vacche allevate giorno e notte al pascolo (1,860 m s.l.m.). Durante l’esperimento, sono state fatte 7 caseificazioni seguendo tecniche tradizionali, una ogni 2 settimane, utilizzando il latte prodotto durante la transumanza (da giugno a settembre). Sono stati raccolti per ogni caseificazione: il latte della mungitura della sera (giorno prima della caseificazione), lo stesso latte il mattino successivo (dopo il processo di scrematura naturale), la panna di affioramento, il latte della mungitura del mattino, il latte in caldaia ottenuta dalla miscela tra il latte scremato della mungitura della sera con il latte della mungitura del mattino, la cagliata, il siero, la ricotta ottenuta dal siero e il residuo della lavorazione ossia la scotta. Inoltre, la cagliata è stata usata per produrre formaggi di “Malga” che sono stati stagionati per 6 e 12 mesi. Le caratteristiche chimico-fisiche sono state misurate con una tecnologia a infrarosso. I risultati dimostrano una variazione della produzione giornaliera e composizione chimica del latte, resa in formaggio e recupero/o perdita di nutrienti nel processo di caseificazione tradizionale. In particolare, si è osservata una riduzione della produzione giornaliera di latte, grasso, proteine e lattosio del latte durante la transumanza estiva. Tuttavia, si è anche osservato un effetto positivo sulla produzione e la composizione chimica del latte del ritorno delle vacche nelle aziende di fondo valle alla fine della stagione dell’alpeggio. La resa media di formaggio in questo lavoro è risultata del 14.2%, mentre i recuperi di grasso, proteine, solidi totali ed energia sono del 85.1%, 77.8%, 49.4% e 58.1%, rispettivamente. Questi risultati sono in linea con quelli trovato in letteratura. Nella seconda parte di questo contributo, è stato misurato il contenuto di composti volatili nello spazio di testa dei campioni con la tecnica SPME/GC-MS. Dopo l’analisi, sono stati identificati 49 VOCs appartenenti alle famiglie chimiche degli alcoli, aldeidi, acidi grassi, chetoni, esteri, lattoni, terpeni e composti solforati e fenolici. Inoltre, è stata studiata l’evoluzione dei VOCs e delle loro famiglie chimiche attraverso i processi di caseificazione, di produzione della ricotta e di stagionatura del formaggio. Il confronto tra la concentrazione dei VOCs dei 4 tipi di latte (intero e scremato della sera, intero del mattino, caldaia) ha dimostrato che il processo di scrematura influenza la concentrazione di metà dei composti volatili analizzati, seguito dall’effetto della mungitura (intero della sera vs. intero del mattino) e dall’effetto del mescolamento (latte scremato della sera mescolato in parti uguali con il latte del mattino). In generale, la panna, rispetto a cagliata e ricotta, ha un maggiore contenuto di acidi grassi, terpeni e composti solforati. Inoltre, la ricotta rispetto alla cagliata ha un’elevata concentrazione di VOC, probabilmente dovuta alla maggiore temperatura utilizzata durante il processo di produzione. L’effetto del progressivo depauperamento di nutriente del latte è stato studiato attraverso il confronto tra latte in caldaia, siero e scotta. Sebbene il latte abbia un maggiore contenuto di nutrienti, il siero e la scotta hanno una maggiore concentrazione di VOC ad eccezione delle famiglie chimiche degli esteri, terpeni, composti solforati e fenolici. Infine, l’effetto della maturazione è stato valutato attraverso il confronto tra le quantità di VOC della cagliata e dei formaggi stagionati (6 e 12 mesi). Il rilascio dei composti volatili incrementa con l’aumento del periodo di maturazione probabilmente dovuto a una maggiore attività enzimatica e microbiologica nel formaggio. In conclusione, le tecniche analitiche di spettrometria di massa utilizzate in questo lavoro (SPME/GC-MS e PTR-ToF-MS) hanno permesso di caratterizzare i composti volatili dei prodotti lattiero-caseari in maniera efficiente. Il sistema di allevamento, le caratteristiche individuali delle vacche hanno influenzato l’impronta aromatica di formaggi individuali stagionati. In particolare, riguardo alle caratteristiche individuali degli animali il principale effetto era lo stadio di lattazione seguito da ordine di parto e produzione giornaliera di latte. Sulla base dei fenotipi raccolti in questo lavoro è stato possibile effettuare un’analisi genetica, la quale ha dimostrato l’esistenza di un’interessante variabilità genetica connessa ai composti volatili del formaggio che potrebbe essere utile per una selezione (in)diretta delle vacche da latte sulla base di aspetti qualitativi in programmi di miglioramento genetico. Tuttavia sono necessarie altre ricerche in quest’area per esempio, nell’era della genomica, sarebbe interessante associare qualche regione specifica del genoma ai composti volatili. L’evoluzione dei composti volatile attraverso la filiera di produzione dipende da specifici aspetti tecnologici, come l’affioramento della panna, la temperatura di coagulazione e il periodo di stagionatura. Il monitoraggio dell’impronta aromatica permette di ottenere prodotti lattiero-caseari con delle specifiche caratteristiche organolettiche utili a differenziare il prodotto sul mercato e a migliorare l’efficienza dell’intera filiera produttiva sulla base di aspetti qualitativi.

Adsorption combined with aqueous phase electrochemical regeneration has been shown by researchers at The University of Manchester (UoM) to offer an alternative approach to the removal of organics from waters and wastewater's. The process, based on a regenerable graphite intercalation compound (GIC) adsorbent, produces no secondary waste, is energy efficient and chemical free. A company, Arvia Technology Ltd., was set up in 2007 to commercialise the technology. As part of a growth and development strategy Arvia investigated other possible applications of the technology and found that odour removal from gas streams might be a good fit with technology features. This Engineering Doctorate (EngD) was a direct investigation into both this technology fit and into the market opportunity for technologies treating odours and volatile organic compounds (VOCs) in gas streams. The research conducted demonstrated that the technology in its different applied forms had certain process drawbacks. Where mass transfer, adsorption and regeneration were combined in a single unit, enhanced transfer as a result of higher pollutant Henry's coefficient was offset by lower adsorbate affinity which varied with hydrophobicity. This relation between affinity and hydrophobicity was different for oxygen functionalised aromatic molecules than for the aliphatic molecules studied. Where adsorption occurred in the gaseous phase and regeneration in the aqueous phase, disadvantages such as short adsorbent packed bed lifetimes and lower current efficiencies of oxidation as a result of adsorbate desorption were shown to be an issue. When the above process challenges were set against the challenging market environment and relatively small market opportunity (approx. £52 million in Europe, 2012) it was difficult to recommend further broad research into the technology. However it was concluded that the concept might still be usefully applied to odour and VOC abatement and that further work should focus on a two phase system with a gas phase adsorbent regeneration technique. The relation observed between adsorbate affinity, hydrophobicity and structure allowed the demonstration of the preferential removal of phenol from solutions containing significantly higher concentrations of aliphatic molecules. This finding is considered the most important project output as it highlights an opportunity to develop Arvia's water treatment technology into a targeted water treatment system for the removal of specific, industrially important, organic contaminants.

The depletion of fossil fuel resources, pollution concerns and the challenge of energy security are driving the search for renewable energy sources. The use of lignocellulosic plant biomass as an energy source is increasing in the United Kingdom and worldwide. In the UK, up to 0.35MHa (6% of total arable land) may be planted with perennial bioenergy crops by 2020 in order to meet renewable energy and CO2 reduction targets. Several plant species that produce high biomass from low inputs have been identified. The most promising for the UK climate are the genus Miscanthus, a perennial rhizomatous grass which can grow up to 3.5m in a year, and short rotation coppice (SRC) willow (Salix spp.), plantations of which can remain viable for up to 30 years. Although bioenergy crops are perceived as “carbon neutral”, changes in land use can have a wider impact on atmospheric composition than through CO2 alone. This study compares vegetation fluxes of methyl halides (CH3Br and CH3Cl) and biogenic volatile organic compounds (BVOCs) from perennial bioenergy crops and annual arable crops at three sites in the UK. Methyl halides are the most abundant natural vectors of bromine and chlorine into the stratosphere and play an important role in stratospheric ozone destruction. BVOCs affect atmospheric oxidising capacity and are a major precursor to the formation of ozone and secondary organic aerosols in the troposphere. Although terrestrial vegetation is an important source of these trace gases there are very few previous measurements of these reactive gases from bioenergy crops. This study describes measurements conducted at two SRC willow sites in Scotland, and one site in England planted with adjacent perennial bioenergy crops and annual arable crops, to quantify and characterise natural methyl halide and BVOC fluxes from vegetation. Measurements were conducted with branch chambers, using static enclosure techniques to measure methyl halide fluxes and dynamic enclosures to measure BVOCs such as isoprene and -pinene. Fluxes were calculated from the concentration difference between background/inlet samples and after enclosure/outlet samples. Methyl halide concentrations were determined by sampling gas from static enclosures followed by analysis using an oxygen-doped GC-ECD with a custom-built pre-concentration unit. Samples for BVOC analysis were collected onto adsorbent tubes and a thermal desorption GC-MS was used to determine BVOC concentrations. Potentially influential environmental variables such as photosynthetically active radiation (PAR), total solar radiation, air temperature, soil temperature, internal chamber temperature and soil moisture were recorded in parallel to the enclosures to determine their potential relationships to fluxes. Long-term environmental data was also available from on-site or nearby weather stations. Long-term measurements were carried out for 2 1 2 years at a site in Lincolnshire, England where adjacent fields are planted with Miscanthus, SRC willow and annual arable crops (wheat and oilseed rape crop rotation). Vegetation measurements were made almost every month throughout the period, with more intensive measurements such as full diurnal cycle carried out during the summer. Ten sampling points are sampled in each field and semi-diurnal measurements are taken regularly. Long-term measurements were also carried out at two sites in Scotland planted with SRC willow, one in Arnot, Perth & Kinross which was sampled for a year and one in East Grange, Fife which was sampled for half a year. Up to 30 sampling points were employed in Arnot and another 10 in East Grange. The bioenergy crops and wheat emitted low fluxes of methyl halides in comparison to the oilseed rape. Mean annual net fluxes of CH3Br and CH3Cl from Miscanthus were 1.8 ng g (dry weight)-1 h-1 and 11 ng g-1 h-1, respectively. At the three willow sites, mean annual net fluxes of CH3Br and CH3Cl ranged between 0.6 - 1.7 ng g-1 h-1, and 1.7 - 12 ng g-1 h-1, respectively. Negligible fluxes of methyl halides were measured from wheat but oilseed rape was found to emit large fluxes of methyl halides with mean annual net fluxes of CH3Br and CH3Cl of 20 ng g-1 h-1and 144 ng g-1 h-1, respectively. The largest BVOC fluxes were measured from SRC willow at the Brattleby site, with high mean annual net fluxes of isoprene (77 μ g g-1 h-1), α -pinene (46 g μg-1 h-1), β -pinene (5.5 μ g g-1 h-1), limonene (3.7 μ g g-1 h-1) and δ -3-carene (11 μ g g-1 h-1). However, mean annual net BVOC fluxes measured at Arnot and East Grange were much lower. High fluxes of - pinene were measured from Miscanthus in 2010 (giving a mean annual net flux of 65 μ g g-1 h-1) but no other significant BVOC fluxes were distinguished. Negligible fluxes of isoprene were measured from wheat but fluxes of monoterpenes were high with mean annual net fluxes of 65 μ g g-1 h-1 and 25 μg g-1 h-1 for α -pinene and limonene, respectively. No significant fluxes of BVOCs were measured from the oilseed rape. All fluxes demonstrated a strong seasonal trend with higher emissions during the summer growing season and low to zero emissions over winter. The high spatial variability was captured by sampling from many points in each field. Some diurnal measurements exhibited a clear pattern of higher emissions during the day and low to zero emissions at night. Some positive correlations between fluxes and environmental variables such as PAR and air temperature were observed. An experiment carried out on willow cuttings in the greenhouse found no clear increase or decrease in fluxes of BVOCs in response to N fertiliser treatment, instead fluxes were found to vary significantly with some of the observed environmental variables. UK estimates were derived by extrapolating measured fluxes using the current respective land cover areas for Miscanthus and SRC willow. Estimated UK annual fluxes of CH3Br and CH3Cl from Miscanthus were 0.01Mgy-1 and 0.05Mgy-1, respectively and from SRC willow were 0.06Mgy-1 and 0.4Mgy-1, respectively, accounting for a very small percentage of total global annual turnover of CH3Br and CH3Cl. Estimated UK annual fluxes of the BVOCs isoprene and α -pinene from Miscanthus were 0.01Mgy-1 and 0.4Mgy-1, respectively and from SRC willow were 3Mgy-1 and 1Mgy-1, respectively. Future planting of SRC willow to meet the UKs energy needs could lead to a potential annual isoprene flux of 150 MgMgy-1.

Aroma and texture are known to influence the overall perception of apple flavour and are subconsciously evaluated by consumers during consumption. Aroma is derived from the volatile organic compounds (VOCs) released from the apple both before (orthonasal) and during consumption (retronasal). The degree to which the VOC impacts upon the flavour profile is affected by the mechanical breakdown of the apple flesh during mastication. The characteristics of apple texture, microstructure and breakdown are cultivar specific. This thesis aimed to understand the cultivar specific differences of apple texture, microstructure and VOC release in relation to their role in overall flavour perception and to explore the correlations between sensory derived attributes and instrumental derived parameters. In vitro (orthonasal) and in vivo (retronasal) measurements of VOC release were carried out using either a proton transfer reaction quadrupole mass spectrometer (PTR-QUAD-MS) or a proton transfer reaction time of flight mass spectrometer (PTR-ToF-MS). Both instrumental techniques separated cultivars based on their in vitro headspace volatile organic compound (VOC) profiles of either intact or cut apple portions. However, PTR-ToF-MS was found to be superior to PTR-QUAD-MS due to its higher sensitivity. The in vivo nosespace method involving the measurements of dynamic VOC release from the nasal cavity, during swallowing as panellists consumed apple portions, resulted in improved data and temporal resolution, as well as an increase in the number of detectable nosespace VOCs when the PTR-ToF-MS was used. Ester related VOCs were predominantly detected in the in vivo nosespace measurements followed by carbonyl and alcohol related compounds. Measured nosespace parameters showed potential for use in understanding differences in the mechanical breakdown of apple flesh during mastication; with for example juicy cultivars inducing a faster time to first swallow (Tswal). Panellists also displayed longer consumption times (Tcon) when consuming firm samples, as opposed to softer cultivars. In a preliminary study using the PTR-QUAD-MS, the time to maximum VOC intensity (Tmax) was found to be shorter for soft apple flesh owing to their faster breakdown during mastication and their resulting increase in surface area. However, the PTR-ToF-MS study which used more cultivars suggested that Tmax could also be shorter for firm juicy cultivars, owing to the occurrence of more swallowing events during mastication as juice was released. The feasibility of being able to differentiate between cultivars using solely instrumental techniques was investigated by comparing instrumentally derived results to those gained from descriptive sensory analysis. Sensory odour/ flavour data was compared to VOC profiles obtained from the PTR-ToF-MS, while sensory texture was compared to mechanical and acoustic textural parameters. Both analytical and sensory techniques characterised the cultivars similarly, indicating the potential of solely instrumental techniques to separate apple cultivars based on their VOC profiles and textural properties. Different VOC groups (terpenes; esters and their associated fragments; butanoate esters) were associated to specific sensory attributes. For example, butanoate esters (m/z 103, 117, 131) were positively correlated to lemon flavour and odour whereas hexyl acetate (m/z 145) was positively correlated to overall apple odour signifying its importance towards base apple flavour. Physico-chemical properties such as titratable acidity (TA) were positively correlated to sour taste which could be considered in prediction models. Sweet taste was negatively correlated to TA but was not correlated to soluble solids content (SSC). However, a positive correlation between sweet taste and fruity ester related compounds (m/z 43, 61, 145) was observed indicating a possible aroma-taste interaction. Instrumentally derived texture parameters were well correlated to sensory descriptions. However, the former also provided additional information that could differentiate between cultivars that were firm but not crunchy. As the behaviour of apple flesh breakdown during mastication was shown to affect perceived texture, X-ray micro-computer tomographic (μ-CT) scanning was used to investigate microstructural differences that could affect apple texture. Morphological properties of apple parenchyma such as connectivity and porosity were associated with VOC release, whereas anisotropy was associated with firm texture. Porosity was negatively correlated to firm texture however, this was cultivar specific owing to the fact that porosity is a summation of all intercellular spaces within a volume; it does not take into account the variation in size and distribution which has been shown to affect texture. The use of an ethylene inhibitor, 1-methylcyclopropene (1-MCP) retained the apple texture at a cost of lower VOC emission. However, its efficacy favoured cultivars of high ethylene concentration (Golden Delicious) as opposed to low ethylene emitting cultivars (Fuji). Therefore, it is important to understand the effects of 1-MCP on specific cultivars. This study demonstrated the viable use of PTR-MS and texture measurements to understand the interrelationships between texture and aroma release during consumption. These techniques were shown to characterise apple cultivars similarly to sensory measurements. Moreover, μ-CT scanning proved to be a powerful tool to visualise the role of microstructure in mechanical texture. Overall, these analyses showed that apple cultivars are distinctly different and suggest that such information could be used to compile a database of phenotypes, such as the cultivar specific VOC and texture characteristics. This database could be used as a reference to create high quality apples through careful selection of specific traits in order to create customised apples targeted towards consumer specific needs.

In this research we are following the thermo-chemical degradation of wood in the absence of oxygen. The objectives are to evaluate the influence of heating rates on pyrolysis products obtained from wood pyrolysis and to evaluate the influence of acid pre-treatment on pyrolysis products. Depending on the wood heating rates, pyrolysis can be categorized as Flash pyrolysis, Fast pyrolysis, and Slow pyrolysis. We have evaluated the volatile products obtained at different heating rates and the volatile products obtained from sulfuric acid pre-treatment by using gas chromatography- mass spectrometry (GC-MS). We have also performed thermo-gravimetric analysis (TGA) of raw wood samples and sulfuric acid pre-treated wood samples of Yellow Pine to determine the changes in weight in relation to change in temperature. Our results indicated that by using the Flash, Fast, and Slow heating rates, the overall volatile products obtained from wood pyrolysis (i.e. the overall list of all the compounds obtained from different temperature ranges in wood pyrolysis by using different heating rates) were the same, but the volatile products obtained at different temperature ranges like Room temperature-300°C, 300°C - 400°C, and 400°C -500°C in Flash, Fast, and Slow pyrolysis were different. Most of the volatile products obtained from the pyrolysis of untreated wood were phenols. Our results also indicated that the pretreatment of wood with sulfuric acid alters the charcoal properties and releases gaseous products including furan derivatives that are useful as fuels or fuel additives. The sulfuric acid (10%) pretreatment of wood followed by slow pyrolysis produced maximum yield of charcoal, indicated by the lowest mass % decrease of 58.234. The production of furan derivatives increased by using sulfuric acid pre-treatment, which is a good improvement for the production of Furanics, the furan based biofuels. The furan based biofuels are of increasing research interest because of their significant advantages over the first generation biofuels. The thermogravimetric analysis (TGA) results indicated that the acid pre-treatment altered the decomposition rate of pyrolysis and lowered the onset of temperature for decomposition. The use of thermal degradation of plants for creating chemicals and fuels is seeing renewed interest across the globe as it is considered carbon-neutral and it uses a renewable feedstock. The information obtained from this research work will also be valued by industries, such as charcoal and activated carbon producers, which currently perform biomass pyrolysis, by allowing them to form approaches that optimize their energy use and minimize waste.

With the increasing time people spend indoors, the indoor environment quality draws more and more attention. The concentration of indoor pollutants is usually much higher than outdoors, in which volatile organic compounds (VOCs) and mold/mildew are both major pollutants and cause many health problems to residents. Efforts devoted from academy and industry to protecting people from indoor environment problems are apparently not sufficient. Photocatalysts, such as TiO2, WO and ZnO, can absorb light photons and react with O2 and H2O to generate highly oxidative radicals, which can oxidize VOCs and disinfect microorganisms. Recently, this photocatalytic oxidation (PCO) technology has been intensively studied to reduce VOCs and disinfect bacteria in the indoor environment. Few papers address the indoor mold/mildew problem, and this research therefore endeavors to do so. The objectives are to evaluate the effectiveness of PCO technology to resist mold/mildew growth and prevent VOC emission from building materials under either UV or visible light irradiation. The models, including linear regression, logistic regression, and numerical model, are also built for interpreting experimental results and for predicting performance in application. The mold/mildew resistance of different PCO gels was examined using accelerated mold/mildew growth agar plate tests. These gels included TiO2 only and TiO2 in combination with H2O2 and with Ag. Without the application of PCO gels, no mold/mildew inhibition was observed from UV (365 nm) or visible light. Under UV light irradiation, the TiO2 gel achieved complete mold/mildew inhibition. Without light, a 12-day delay of mold growth was obtained using the Ag-TiO2/H2O2 gel. Under visible light irradiation, the Ag-TiO2/H2O2 gel was also the most effective PCO gel with a 8-day delay of mold growth, which, however, was shorter than the same gel in the condition of no light with a 10-day delay due to the light-induced deterioration of the Ag-TiO2. The reduction of VOC emission from PCO gel (TiO2 gel and Ag-TiO2/H2O2 gel) coated building materials under UV or visible light irradiation was also confirmed by small chamber tests (the Ag-TiO2/H2O2 gel with above 50% reduction of total VOC emission). A linear model was obtained for the Ag-TiO2/H2O2 gel in the condition of no light, with respect to the correlation between the delay of mold growth and the gel ingredients. A logistic model was created for predicting the probability of mold growth on different TiO2 gels with different UV light exposure time at different intensities. A numerical model was developed with better accuracy than the previous one for VOC emission from PCO gel coated building materials. This study showed that the PCO gel might be a promising multifunctional material in resisting mold/mildew growth and preventing VOC emission in the indoor environment (The TiO2 gel for complete mold/mildew inhibition and the Ag-TiO2/H2O2 gel for delay of mold growth in emergency situations and reduction of VOC emission from building materials). More stable Ag-TiO2 or other visible-light-driven photocatalysts are needed in future research because of the deterioration of the current one.

An evaluation of the VOC (Volatile Organic Compound) emissions monitoring system of Natref (National Refiners of South Africa) was conducted to determine the effectiveness of the system. Natref monitors fugitive plant equipment VOC emissions, VOC emissions from the wastewater treatment area and the tank farm as separate entities. The hiatus in the VOC emissions monitoring system is the absence of an overall VOC emission scenario at Natref. Data of VOC emissions from Natref's field data were used to determine the overall VOC emission scenario at the refinery. Since no control guidelines are available for VOC emissions in South Africa. it was necessary to with refineries in the USA and Western Europe to determine how effective Natref’s VOC emissions monitoring system is. The percentage VOC emissions at Natref from the three areas fell outside the benchmark ranges and different scenarios were simulated to determine the possible causes. The results of this evaluation brought to light inadequacies in the VOC emissions monitoring system at Natref and an estimated loss of approximately three million rand per annum due to VOC emissions. The absence of a coherent picture of VOC emissions at the refinery can lead to sub-optimal expenditure of resources to reduce VOC emissions. The value of a monitoring system lies therein that information obtained from it can be used to implement effective control measures in order to make a contribution to the protection of the environment and therefore towards sustainable development.
Thesis (M. Environmental Management)--North-West University, Potchefstroom Campus, 2005.

Colorectal cancer (CRC) is the one of the commonest causes of cancer and cancer related death worldwide. Its aetiology is linked to a number of reversible and irreversible genetic and environmental factors, including age, sex, genetics, smoking and diet. There has been a drive in recent years for non-invasive biomarkers for many malignant and non-malignant diseases across multiple medical specialties. One of the areas of interest is the detection of volatile organic compounds (VOCs) in various bodily substances by means such as mass spectrometry and electronic noses. CRC patients have been shown to be distinguishable from healthy controls using urinary VOC detection in several studies, including two published by the research group at UHCW and the University of Warwick. There has also been much interest in recent years into the role that the intestinal microbiome plays in health and disease in humans. The aim of this thesis was to characterise the urinary VOC and stool microbiome profiles of CRC patients, their spouses and first degree relatives. The aim being to determine whether the urinary VOC profiles could be distinguished using this technology and to try and better understand the underlying mechanism which lead to CRC carcinogenesis. The first degree relatives and spouses were selected as “common gene pool” and “shared environment” control groups respectively. This work was done using an LC-FAIMS-MS hybrid machine to detect urinary VOCs and 16s RNA sequencing using an Illumina Miseq platform. Comparisons were also made between pre-treatment and post-treatment CRC samples to try and determine if there was any change in either VOC or microbiome profiles after CRC treatment. The urinary VOC profiles of CRC subjects could be distinguished from both sets of healthy controls using a 5-fold cross validation and sparse logistics regression and Random Forrest statistical classifiers, achieving sensitivities of 63-69%, specificities of 64-69% and AUC 0.71-0.72. No statistically significant differences could be found in the urinary VOC profiles of pre-operative and post operative samples. Microbiome analysis revealed over 1300 operational taxonomic units (OTUs), with a similarity of >93% between the CRC samples and the control groups, with significantly different bacterial abundances identified in only 82 OTUs (6.2%), mainly Clostridiales bacteria. Pre-treatment and post-treatment sample analysis revealed differences of 17 (3%) and 22 (4%) OTUs at 3 and 6 months respectively, again principally clostridiales. This thesis provides further data on the microbiome composition in CRC. It also provides further proof of the utility of urinary VOCs, for the first time here using LC-FAIMS-MS technology, a variant of the previously utilised FAIMS technology, as a non-invasive biomarker for CRC.

Volatile organic compounds (VOCs) from biogenic and anthropogenic sources are important constituents of the atmosphere with effects on air quality and climate. Current uncertainties in measurements and models relate to their roles in tropospheric ozone and secondary organic aerosol formation, yet there have been few measurements of their fluxes from contrasting chemical environments. Additional measurements with greater spatial and temporal resolutions are required to constrain uncertainties in atmospheric chemistry and climate models. This thesis presents long-term measurements of VOC fluxes and concentrations in two contrasting environments: central London and the Brazilian Amazon. VOC concentrations were quantified by proton transfer reaction-mass spectrometry and fluxes were calculated using the virtual disjunct eddy covariance method over a period of several months at sites in central London and the Amazon rainforest. In central London, traffic was found to be the main source of aromatic compounds. Oxygenated compounds and isoprene showed strong correlations with light and temperature, suggesting biogenic, evaporative, or secondary atmospheric origins. The seven VOCs measured in central London had a five-month average total emission rate of 1.4 mg m-2 h-1. Comparisons with local and national emission inventories showed that modelled emissions were largely underestimated. Measurements of isoprene and monoterpenes at the remote ZF2 site in the Amazon rainforest showed an 11-month average total emission rate of 2.7 mg m-2 h-1 with considerable seasonal variation, which could not be accurately reproduced using the light and temperature based MEGAN algorithms. This thesis presents the first long-term VOC flux measurements providing information at high temporal resolutions on seasonal variability at an urban site and a pristine tropical forest site. They confirm that the Amazon rainforest is an extremely strong source of reactive carbon to the Earth’s atmosphere exceeding emissions from a developed megacity, such as London, per unit area.

As a result of increased terrorist activity around the world, the development of a canine training aid suitable for daily military operations is necessary to provide effective canine explosive detection. Since the use of sniffer dogs has proven to be a reliable resource for the rapid detection of explosive volatiles organic compounds, the present study evaluated the ability of the Human Scent Collection System (HSCS) device for the creation of training aids for plasticized / tagged explosives, nitroglycerin and TNT containing explosives, and smokeless powders for canine training purposes. Through canine field testing, it was demonstrated that volatiles dynamically collected from real explosive material provided a positive canine response showing the effectiveness of the HSCS in creating canine training aids that can be used immediately or up to several weeks (3) after collection under proper storage conditions. These reliable non-hazardous training aids allow its use in areas where real explosive material aids are not practical and/or available.

Il monitoraggio biologico è un utile approccio per valutare l'esposizione umana a sostanze inquinanti. Lo scopo di questo progetto è stato quello di sviluppare nuovi metodi analitici per il biomonitoraggio dell'esposizione umana a inquinanti organici volatili e persistenti, oltre alla loro applicazione a determinati gruppi di soggetti e ad un confronto tra diversi approcci (approcci mirati e non-mirati). Un metodo in spettrometria di massa tandem accoppiato con la cromatografia liquida in fase inversa (HPLC-MS/MS) è stato sviluppato per l'analisi di un totale di 17 acidi mercapturici urinari, metaboliti di diversi composti organici volatili. È stata eseguita una completa validazione includendo precisione, accuratezza, linearità, sensibilità, efficienza del processo di preparazione del campione e verifica esterna. Questo metodo è stato applicato a un gruppo di 49 lavoratori di una cokeria e 49 individui non-esposti che vivevano nella stessa area geografica. Il fumo di tabacco è stato un criterio di esclusione per entrambi i gruppi. I livelli urinari dei metaboliti di benzene, stirene, acrilonitrile e 1,3-butadiene erano da 2 a 10 volte più alti nei lavoratori rispetto ai controlli. Il metodo è stato applicato anche a un gruppo di soggetti con diverse abitudini al fumo, in particolare: 38 non-fumatori (NS), 7 utilizzatori di sigarette elettroniche (ECU) e 22 fumatori di sigarette tradizionali (TTS). La maggior parte degli acidi mercapturici misurati era da 2 a 165 volte più alta nei TTS rispetto ai NS. I metaboliti di acrilonitrile e acroleina erano, rispettivamente, 1.8 e 4.9 volte più alti nei ECU rispetto ai NS. Inoltre, confrontando i fumatori con i lavoratori della cokeria non fumatori, i primi sono stati esposti a una maggiore quantità di composti organici volatili. Un approccio di metabolomica non-mirata è stato applicato alla stessa popolazione di soggetti con diverse abitudini al fumo. I campioni sono stati analizzati mediante cromatografia liquida accoppiata a spettrometria di massa a tempo di volo. Tra i composti putativamente annotati vi erano il glucuronide coniugato della 3-idrossicotinina e il coniugato solfato del metossifenolo. Considerando gli acidi mercapturici, la coerenza tra l'approccio mirato e quello non mirato è stata trovata per un numero limitato di sostanze chimiche, tipicamente le più abbondanti. Infine, è stato sviluppato un metodo HPLC-MS/MS per la determinazione di alcune sostanze interferenti con il sistema endocrino. Le molecole analizzate comprendevano bisfenolo A e metaboliti di ftalati, inclusi tereftalati in quanto prodotti sostitutivi emergenti. È stata effettuata una completa validazione e il metodo è stato applicato a 36 adulti non esposti professionalmente.
Biomonitoring is a useful approach to assess the exposure to pollutants in human subjects. The aim of this project was the development of new analytical methods for the biomonitoring of exposure to volatile and persistent organic pollutants, their application to selected groups of subjects, and a comparison between different approaches (untargeted vs targeted approaches). A high-throughput isotope dilution tandem mass spectrometric method coupled with reversed-phase liquid chromatography (HPLC-MS/MS) was developed for the analysis of a total of 17 urinary mercapturic acids, as metabolites of several volatile organic compounds. A complete validation was carried out including precision, accuracy, linearity, sensibility, process efficiency, and external verification. This method was applied to a group of 49 coke-oven workers and 49 individuals living in the same area. Active tobacco smoking was an exclusion criterion for both groups. Urinary levels of the metabolites of benzene, styrene, acrylonitrile, and 1,3-butadiene were 2–10 fold higher in workers than in controls. The method was also applied to a group of subjects with different smoking habits, in particular: 38 non-smokers (NS), 7 electronic cigarette users (ECU), and 22 traditional tobacco smokers (TTS). Most of the measured mercapturic acids were 2 - 165 fold-higher in TTS compared to NS. The metabolites of acrylonitrile and acrolein were 1.8 and 4.9 fold-higher higher in ECU than NS, respectively. Furthermore, comparing smokers to non-smoking coke oven workers, the first were exposed to a greater amount of volatile organic compounds. An untargeted metabolomic approach was applied to the same population of subjects with different smoking habits. Samples were analysed by liquid chromatography/time-of flight mass spectrometry. Among putatively annotated compounds there were the glucuronide conjugated of 3-hydroxycotinine and the sulfate conjugate of methoxyphenol. Considering mercapturic acids, the coherence between the targeted and untargeted approach was found for a limited number of chemicals, typically the most abundant. Finally, an HPLC-MS/MS method for the determination of some endocrine-disrupting persistent chemicals was developed. Targeted molecules were bisphenol A and metabolites of phthalates, including emergent terephthalates. A complete validation was carried out and the method was applied to 36 non-occupationally exposed adults.

Thesis (M.S.)--University of North Carolina at Chapel Hill, 2006.
Title from electronic title page (viewed Oct. 10, 2007). "... in partial fulfillment of the requirements for the degree of Master of Science in the Department of Environmental Sciences and Engineering." Discipline: Environmental Sciences and Engineering; Department/School: Public Health.

Volatile organic compounds (VOCs) can be related to different compound classes but they all have a distinct vapour pressure allowing them to enter the atmosphere under ambient conditions. VOCs can undergo various reactions in the atmosphere and are emitted by various processes (anthropogenic and natural). Compound specific isotope analysis (CSIA) has been used in many other research studies to track the fate and source of compounds in the environment and the geological record. The majority of CSIA has been applied to extracts from soil, sediment or crude oils requiring entirely different sampling techniques compared to atmospheric samples. Applying CSIA to atmospheric compounds is a growing research field but has mainly being restricted to stable isotopes of carbon.This PhD thesis presents a novel application for adsorptive sampling on TenaxTA to analyse compound specific δ13C and δD of a range of atmospheric VOCs (C6 - C10). For the first time a 2-stage thermal desorption (TD) unit was linked to gas chromatography isotope ratio mass spectrometry (GC-irMS) and instrumental conditions were thoroughly investigated and optimised. Results obtained by using a standard mix of eleven VOCs confirmed reliability of TD-GCirMS analyses with standard deviations (SD) below instrument precision. δ values showed negligible isotopic fractionation compared to results obtained from traditional GC-irMS analysis (without TD unit) demonstrating the suitability of TD for CSIA.The technique was applied to analyse VOCs from various emission sources, e.g. car exhaust, biomass combustion and an industry stack. The results obtained have provided some insight into the formation processes of the VOCs investigated. δ13C values from an alumina refinery emission support a natural origin for the VOCs (organic material in bauxite ore). The δD values (21 to - 137 ‰) of the industry emission were consistently more enriched in D compared to δD values of VOCs previously reported making the δ values of VOCs in the industrial stack unique. Car exhaust emission from a petrol engine showed significant differences in δ values for VOCs up to 2 ‰ and 25 ‰ (δ13C and δD, respectively) at different tank fuel levels when using the same fuel batch. Car exhaust emission samples from a diesel engine showed a high content of highly complex mixture of unresolved compounds thus chromatographic baseline separation of VOCs was not achieved for stable hydrogen isotope analysis and led to unreliable δ values. The results from different biomass combustion emissions (including 5 species of C3 plants and 3 species of C4 plants) confirmed significant differences in δ13C of VOCs between C3 and C4 plants due to their specific metabolic pathways for carbon fixation in photosynthesis. The δD of VOCs derived from dicotyledons were less depleted in D compared to δD of VOCs derived from grasses (differences >27 ‰) indicating that the VOCs are derived mainly from lignin/cellulose rather than from lipids since dicotyledons contain higher amounts of lignin/cellulose.Due to the unique isotopic signatures of the VOCs from the different emission sources it was possible to distinguish their origins. Furthermore, TD-GC-irMS shows great potential to establish other emission sources in the environment and may help to gain some insight into their modes of formation.

Isoprene is the most abundant volatile organic compound (VOC) emitted from vegetation, mainly trees. Because it plays an important role in tropospheric chemistry leading to formation of pollutants and enhancing the lifetime of the greenhouse gas methane, concern about the response of isoprene emissions to the rise in atmospheric CO2 concentration and global climate change has been increasing over the last few years. The consequences of predicted climate change will have complex repercussions on global isoprene emission. The increasing atmospheric CO2 per se will have direct effects on terrestrial vegetation since CO2 is the substrate of photosynthesis. Because photosynthesis is limited by CO2 at current ambient concentrations, an increase in CO2 is expected to increase leaf biomass (i.e. isoprene emitting surface). Predicted warmer climate, extended drought periods, the possible shift in plant species in favour of isoprene emitters and the increase in length of growing season, may cause an increase in global isoprene emissions with profound perturbations of air quality and the global carbon cycle. The aim of this thesis was to investigate the effect of environmental variables such as light, temperature, drought and leaf-to-air vapour pressure deficit (VPD), and the short- and long-term effect of atmospheric [CO2] on isoprene emission from temperate and tropical tree species. Both leaf and whole ecosystem level fluxes were studied. At the leaf scale, a short-term experiment with leaves of potted two-year old trees of Quercus virginiana was carried out, exposing plants to two drying-rewatering cycles. Leaf isoprene emission fell, but the process was considerably less sensitive to water stress than photosynthesis and stomatal conductance. In drought conditions, the large reduction in photosynthesis caused the percentage of fixed carbon lost as isoprene to increase as plants became more stressed, reaching peaks of 50% when photosynthesis was almost zero. Isoprene emissions also showed a strong negative linear relationship with pre-dawn leaf water potential (psi-leaf). In another experiment carried out at the large enclosed facility of Biosphere 2 (B2L, Arizona, USA), studying isoprene emission from leaves of three-year-old plants of Populus deltoides grown at three CO2 atmospheric concentrations (430, 800 and 1200 mu mol mol-1 CO2) in non-stressed conditions, instantaneous increases in atmospheric [CO2] always resulted in a reduction of isoprene emission and a stimulation of photosynthesis. Moreover, in the long-term, the CO2 inhibition effect for isoprene emission became a permanent feature for plants growing under elevated [CO2]. Again, isoprene emission was less responsive to drought than photosynthesis. Both water-stress and high VPD strongly stimulated isoprene emission and depressed photosynthetic rate as a result of stomatal closure and the resulting decreases in intercellular [CO2] (Ci). This also led to a dramatic increase in the proportion of assimilated carbon lost as isoprene. The effect of atmospheric elevated [CO2] and its interaction with high VPD and water stress on ecosystem gross isoprene production (GIP) and net ecosystem exchange of CO2 (NEE) in the Populus deltoides plantations was also studied. Although GIP and NEE showed a similar response to light and temperature, NEE was stimulated by elevated CO2 by 72% and depressed by high VPD, while GIP was inhibited by elevated CO2 by 58% and stimulated by high VPD. Similar to what was observed at leaf level, under water stress conditions GIP was stimulated in the short term and declined only when the stress was severe, whereas NEE started to decrease from the beginning of the experiment. This contrasting response led the percentage of assimilated carbon lost by the ecosystem as isoprene to increase as water stress progressed from 2.5% and 0.6% in well-watered conditions to 60% and 40% for the ambient and the elevated CO2 treatments, respectively. Again, we found water limitation and high VPD off-set the inhibitory effect of elevated CO2, leading to increased isoprene emissions. The effect of a mild water stress on GIP and gross primary production (GPP) was also observed in the model tropical rainforest mesocosm of B2L. Although GPP was reduced by 32% during drought, GIP was not affected and correlated very well with both light and temperature. The percentage of fixed C lost as isoprene tended to increase during drought because of the reduction in GPP. Consumption of isoprene by soil was observed in both systems. The isoprene sink capacity of litter-free soil of the agroforest stands showed no significant response to different CO2 treatments, while isoprene production was strongly depressed by elevated atmospheric [CO2]. In both mesocosms, drought suppressed the sink capacity, but the full sink capacity of dry soil was recovered within a few hours upon rewetting. In summary, elevated CO2 increased biomass production and photosynthesis while depressing isoprene production. However, both drought and VPD may off-set the CO2 effect and lead to enhanced isoprene emission. We conclude that the overall effect of global climate change could be of enhancing global isoprene emissions while depressing the soil sink, and that the soil uptake of atmospheric isoprene is likely to be modest but significant and needs to be taken into account for a comprehensive estimate of the global isoprene budget.

Detection canines represent the fastest and most versatile means of illicit material detection. This research endeavor in its most simplistic form is the improvement of detection canines through training, training aids, and calibration. This study focuses on developing a universal calibration compound for which all detection canines, regardless of detection substance, can be tested daily to ensure that they are working with acceptable parameters. Surrogate continuation aids (SCAs) were developed for peroxide based explosives along with the validation of the SCAs already developed within the International Forensic Research Institute (IFRI) prototype surrogate explosives kit. Storage parameters of the SCAs were evaluated to give recommendations to the detection canine community on the best possible training aid storage solution that minimizes the likelihood of contamination. Two commonly used and accepted detection canine imprinting methods were also evaluated for the speed in which the canine is trained and their reliability. As a result of the completion of this study, SCAs have been developed for explosive detection canine use covering: peroxide based explosives, TNT based explosives, nitroglycerin based explosives, tagged explosives, plasticized explosives, and smokeless powders. Through the use of these surrogate continuation aids a more uniform and reliable system of training can be implemented in the field than is currently used today. By examining the storage parameters of the SCAs, an ideal storage system has been developed using three levels of containment for the reduction of possible contamination. The developed calibration compound will ease the growing concerns over the legality and reliability of detection canine use by detailing the daily working parameters of the canine, allowing for Daubert rules of evidence admissibility to be applied. Through canine field testing, it has been shown that the IFRI SCAs outperform other commercially available training aids on the market. Additionally, of the imprinting methods tested, no difference was found in the speed in which the canines are trained or their reliability to detect illicit materials. Therefore, if the recommendations discovered in this study are followed, the detection canine community will greatly benefit through the use of scientifically validated training techniques and training aids.

High Density Polyethylene (HDPE) is a commonly used polymer for food and beverage packaging, but tends to have issues with plastic off-taste. Current industry practice for monitoring and controlling taste quality of HDPE packaging involves sensory analysis by a panel of human analysts. This method of data collection is time consuming, labor intensive, and subjective. As an alternative, multivariate statistical methods may be used to correlate volatile organic compound profiles of HDPE packaging to organoleptic quality of the material.

This study explores the use of multiple linear regressions, principal component regression, and partial least squares regression for predicting organoleptic quality of HDPE packaging. Cross validation was performed for all models to estimate prediction performance. Results of cross validation show that partial least squares in combination with variable selection lead to the best prediction performance. Lastly, linear discriminant analysis was performed for classifying HDPE packaging into organoleptic quality categories.

Among the numerous beneficial effects of phospholipides can highlight their role in protecting the cardiovascular system and improving memory and learning. These effects can be partially explained by the fact that phospholipids are rich in polyunsaturated (eicosapentaenoic and docosahexaenoic acids) or essential fatty acids. Thus, it is very significant to explore potential food sources containing polyunsaturated rich phospholipids for the development new food products supplemented with phospholipids.This work allowed a series method for the extraction, purification, separation and quantification of phospholipids in order to characterize the polyunsaturated phospholipid sources. Food supplementation with polyunsaturated phospholipids rises however the question of their stability during food processing at high temperature. Then we have developed methods to identify phospholipids degradation products and determine their kinetics of the oxidation during thermal treatment which is a widespread food processing.Phospholipids (PE and PC) are more stable than triacylglyceride, this is due to the presence of an amino group in the molecule.