Dissertations / Theses: 'Solid-phase extraction'

1

Zhao, Qing. "Pseudostationary Phase for Solid Phase Extraction." TopSCHOLAR®, 2006. http://digitalcommons.wku.edu/theses/988.

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A unique pseudostationary phase for Solid Phase Extraction is presented. This pseudostationary phase consists of surfactant, which is initially immobilized onto hydrophilic cation exchange resin. The surfactant chain through hydrophobic interactions extracts hydrophobic analytes in the same manner as conventional bonded alkyl moieties on silica based non-polar sorbents. Although hydrophobic analytes can be efficiently trapped on commercially available non-polar sorbents (i.e. Ci8 silica), organic solvents that are necessary to break strong hydrophobic interactions between the analytes and the sorbent are harmful. They are also incompatible for direct introduction into a reversed phase liquid chromatographic set up. In the presented approach, the entire pseudostationary phase may be removed via ion exchange in very mild aqueous solutions, resulting in very efficient elutions with a final extract that is mild and reversed phase liquid chromatographic compatible. Rinse solution parameters were optimized and various cationic surfactants attached to cation exchangeable silica including silica modified with sulfopropyl groups and unmodified silica were investigated to reach sufficient sorbent hydrophobicity to capture EPA 16 priority polycyclic aromatic hydrocarbons (PAHs). PAHs were preconcentrated from river water and were determined using fluorescence detector coupled to high performance liquid chromatography (HPLC). Detections limits for all PAHs examined were lower than EPA's maximum contaminant level.

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Shahtaheri, Seyyed Jamaleddin. "Trace pesticide analysis using immuno-based solid-phase extraction." Thesis, University of Surrey, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336497.

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Ca, Diep Vu. "NANOSTRUCTURED ASSEMBLIES FOR SOLID PHASE EXTRACTION OF METAL IONS." Miami University / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=miami1107552000.

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4

Oakes, Tony. "Silica Based Solid Phase Extraction Sorbent with a Removable Alkyltrimethylammonium Surfactant Phase." TopSCHOLAR®, 2003. http://digitalcommons.wku.edu/theses/559.

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Presented is a solid phase extraction (SPE) sorbent having a removable "stationary phase." This removable phase that consists of alkyltrimethylammonium surfactant is initially immobilized onto hydrophilic strong cation exchange resin. The surfactant chain through hydrophobic interactions extracts hydrophobic analytes in the same manner as conventional bonded alkyl moieties on silica based non-polar sorbents. For the extraction of very hydrophobic species with conventional sorbents, solvents used for analyte elution are generally toxic and not directly instrument compatible. The chosen solvent must be strong enough to efficiently break hydrophobic interactions between the analyte and sorbent. Using a removable "stationary phase," hydrophobic interactions need not be broken between the analyte and the sorbent. In the presented approach, the surfactant ("stationary phase") is removed via ion exchange with exchange ions in very mild aqueous based and instrument compatible solutions. The analyte, being associated with the surfactant, is also removed in the process. Very efficient elutions of hydrophobic analytes are a direct benefit of having a removable "stationary phase." Rinse solution parameters explored include exchange cation type and concentration, and alcohol type and concentration. The extraction of three polyaromatic hydrocarbons, naphthalene, pyrene and benzo(ghi)perylene, is investigated using this sorbent material. A silica based strong cation exchange resin (SCX-2) having a sulfopropyl group is explored and compared with the commercially available silica based extraction sorbent.

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Bartuma, Ninorta. "Optimizing purification of oligonucleotides with reversed phase trityl-on solid phase extraction." Thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-76844.

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Oligonucleotides are synthetic strings of DNA or RNA used mostly for biochemical analysis and diagnostics. For them to be useful in these fields, a purity over 90% is most often required. However, when synthesizing these sequences, many “failures” (shorter sequences) are made in the step-wise process. The synthesized oligonucleotides need to therefore be purified. This is most often done with gel electrophoresis or liquid chromatography. These methods are, on the other hand, very time-consuming and laborious. Solid phase extraction (SPE) is a much faster purification method if optimized and it can be done with the standard cartridges as well as 96-well plates, that allow many samples to efficiently be run at the same time. With reversed phase (RP) SPE, the dimethoxytrityl (DMT) group, that is attached to the target at the final synthesis step, can be used for stronger retention to the bed sorbent and leaving only the target at the final eluting stage. The impurities without a DMT-on group, that do not adsorb to the sorbent, are washed away in earlier steps. The purpose of this study is to optimize an SPE method for purification of oligonucleotides. Two different cartridges, Clarity QSP (Phenomenex) and Glen-Pak (Glen Research) were used. The purity analysis and oligonucleotide identification were done using anion exchange - high performance liquid chromatography (AIE-HPLC) and time-of-flight mass spectrometry (TOF MS). To conclude, Clarity QSP achieved, at the most, a purity of 68.8% with the recommended SPE steps by Phenomenex. Alterations in the extraction procedure resulted in similar purity or lower. Glen-Pak reached a peak purity of 78.8% when doing a double salt wash of 5% ACN in 2 M sodium chloride and another double wash after detritylation with 1% acetonitrile. This method has to be further optimized in order to reach a purity of at least 90% to be useful in industrial settings.

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Karlsson, Tufuga Anna. "Extraction efficacy of oil samples in forensic investigations using solid phase extraction (SPE)." Thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-84464.

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This study aims to complement the internationally implemented method “CEN/TR 15522-2: 2012 WATERBORNE PETROLEUM AND PETROLEUM PRODUCTS - PART 2” (CEN). It is a method for forensic investigations on oil spill identification using gas chromatography coupled with low resolution mass spectrometry in electron ionisation mode (GC-EI-MS), in single ion monitoring mode (SIM). The method uses hydrocarbon fingerprints and biomarker abundances to compare oils from spill sources with oil from suspected sources. This method is implemented by the national forensic centre (NFC) with their main object to perform and develop forensic investigations for successful law enforcement. The experiment uses four different matrices common within the NFC department: wood ash, soil, fabric and cotton swabs. The method evaluates how different sample preparation and clean-up techniques can extract crude oil and heavy fuel oil without losing important information such as the relative abundance of so-called biomarkers typically looked for in international standard praxis in forensic investigations. In conclusion the implemented CEN method showed a reasonably good extraction from matrixes. Extraction of biomarkers were generally quantitative. Extractions of PAHs worked best in soil and cotton swab matrices. In ash samples, the extraction was not very efficient (between 20-80%). It seems that the PAHs strongly bind to active coal in the ash and cannot be extracted fully. It was also evident that the fabric matrix used was problematic for PAH extraction. The fabric itself seemed to release compounds which interfere with the analysis. In soil samples, 31abR (a biomarker compound) was a reoccurring interference from the matrix. Furthermore, analysis of isoprenoids and alkanes had a very broad analytical variation, seen by that the analytical response for these compounds vary greatly among different samples. SPE-extractions did not work well enough following the protocol in this study to be included as a sample preparation step at the moment. More optimization would be needed before the method could be included as an implemented method.

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Morrison, Erin R. "Can We Re-use “Single-Use” Solid Phase Extraction Cartridges?" Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/7065.

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Organic and inorganic compounds are present as contaminants in varying concentrations throughout our water cycle. Examples of these contaminants include the endocrine disrupting compounds (EDCs) bisphenol-A (BPA) and 17β-estradiol (E2) from plastics and pharmaceutical use. It can be necessary to obtain the concentration of these compounds within the water cycle for analysis by interested parties such as research groups, regulatory agencies, and private organizations. These concentrations, however, can be too dilute within the initial sample for analysis. Therefore it is necessary to concentrate the compound of interest (analyte) prior to analysis. One such way to do this is by way of Solid Phase Extraction (SPE). SPE uses a small cartridge which contains chromatographic packing material to chemically extract analytes from a water sample onto a solid phase. To increase concentration, these analytes are then transferred (eluted) to a substantially smaller volume of organic solvent for eventual analyses. These commercially available cartridges are relatively inexpensive, approximately $5 each. However, these cartridges are labeled as single use. In large-scale analyses, this can quickly add up to a sizable percentage of the analysis budget. Additionally, sizable waste volumes can be generated from these analyses in the form of non-degradable polypropylene plastic. If these cartridges can be re-used, material costs as well as waste volumes can be substantially reduced. However, little is known regarding how the quality of analysis degrades with cartridge re-use. The objective of this project is to evaluate the number of times SPE cartridges can be reused without compromising the results of the subsequent analyses. Based on a review of prior literature, I identified and developed protocols for extracting analytes (BPA and E2) from water via SPE, then analyzing them with gas chromatography and mass spectrometry (GC-MS). These protocols have been developed to mimic those employed by research labs, industry, and other entities for which the results of this study would be most applicable. The only deviation is the re-use of the cartridge rather than disposal and replacement. One type of commercially available SPE cartridge (Oasis HLB, Waters Inc., Milford, MA) was used and two water types were tested. The water was spiked with fixed concentrations of BPA and E2, and then analyzed by way of SPE/GC-MS. For both water types, I performed multiple SPE runs on 10 cartridges each. I tracked the history of GC-MS peak areas, which indicate apparent analyte concentration. Peak area data were analyzed as a function of the number of analyses performed (run number), and evaluated for statistically significant changes as well as overall trends. Statistically significant change and/or trends would indicate that the cartridge had exceeded the maximum allowable number of re-uses and would thereby identify the number of times the “single-use” cartridge can reliably be re-used. Peak area history for 20 SPE runs per cartridge for pure water samples and 10 SPE runs for wastewater effluent showed no statistically significant changes or trends on peak area. This indicates that cartridges can be re-used at least 10 times without compromising the integrity of water sample analysis for the EDCs considered in this study.

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Saulitis, Barbara Susan. "Solid phase extraction of aldosterone and analysis using amperometric detection /." Connect to online version, 1996. http://hdl.handle.net/1989/3559.

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Rashid, Badrul Amini Abdul. "Development of selective solid phase extraction sorbents for drug bioanalysis." Thesis, University of Surrey, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244830.

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10

Raisglid, Margaret Ellen. "Factors affecting the selectivity and efficiency of solid-phase extraction." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282246.

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The modified surface of solid phase extraction sorbents is studied with respect to the impact on the isolation and purification of analytes. Interactions at the interface are characterized by quantifying recoveries of a broad range of analytes, on a variety of surfaces, and under various extraction conditions. Bonded phases of varying hydrocarbon chain length are studied. A hydrophobic surface (e.g., C18) favors the retention of small polar compounds, while a more polar surface (C2) favors the elution of larger hydrophobic compounds. A compromise phase (C8) improves overall recoveries, while analyte recoveries were optimized by extraction onto stacked and layered phases. Analytes are retained by different mechanisms and under different solvent conditions. Selective elution of analytes is achieved by judiciously choosing the elution solvent. Data obtained from comparing the time requirements for drying various phases are consistent with previously developed models of the bonded silica surface. The impact of the presence of water on the elution of analytes is also studied. Experiments are presented where increasing concentrations of organic solvent are added to the sample matrix. Recoveries for polar compounds dropped as the matrix became more energetically favorable. Recoveries improved for hydrophobic species as the formation of agglomerations was disrupted. The impact of sample loading rates on analyte recoveries is studied. No significant differences in recoveries of a broad range of non-ionizable analytes are observed for loading rates ranging from 8 to 30 mL per minute on a 13 mm diameter x 15 mm height sorbent bed. The impact of the porous nature of the extraction sorbent on analyte recoveries, under different conditions of temperature and solvent contact time, is studied. A dependence on the diffusion of analytes into and out of the pores is observed. Experiments are devised to characterize the role of particulates in the sample matrix during solid phase extraction. Parameters studied include size of particles in the matrix, in the sorbent bed, porosity of the frit retaining the sorbent, and utility of a depth filter. Samples laden with particulates are spiked with trace analytes and show no reduction in recoveries resulting from the presence of particulate matter.

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11

Stadelmann, Iris Patricia. "Extraction of alcohols from gasoline using solid phase microextraction (SPME)." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/32976.

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It is common practice to add oxygenates, such as ethers or alcohols, to gasoline in areas suffering from ozone or smog problems in order to reduce pollution. The most commonly used oxygenates are ethanol (EtOH) and methyl tert-butyl ether (MTBE). However, MTBE is now forbidden by the environmental protection agency (EPA) because of the possibility of ground water contamination. The current trend is to use EtOH, therefore this work focuses on the analysis and quantification of EtOH in gasoline by solid phase microextraction (SPME). The major problem in quantifying EtOH in gasoline is the coelution of hydrocarbons with EtOH. There have been several approaches to solve this problem; among the chromatographic ones, three major types have been proposed: (1) the first one uses a detector selective for oxygen containing compounds; (2) the second one uses two or more columns; (3) and the third one uses an extraction step prior to GC analysis. In this work an extraction step with water is used prior to a solid phase microextraction (SPME) sample preparation coupled to a gas chromatographic (GC) analysis.

Solid phase microextraction is a recent technique, invented by Pawliszyn in 1989, and available commercially since 1994. A fiber is used to extract small amounts (ppm, ppb, ppt) of analytes from a solution, usually water. The fiber is beneficial in concentrating analytes. Most work using SPME has been done with hydrophobic (non polar) analytes, extracted using a polydimethylsiloxane (PDMS; non polar) coating on a fused silica fiber. Since very little work has been done with polar analytes, the novel approach of this work is the extraction of EtOH.

Since EtOH is the analyte of interest, a polar fiber, carboxen/polydimethyl siloxane (Car/PDMS) is used. Two methods are used for quantification of EtOH in gasoline: the method of a standard calibration curve, and the method of standard addition. They are both successful in quantifying the amount of EtOH in gasoline. The relative errors, with the method of standard addition, vary from 5.3% to 14%, while the ones with the method of calibration curve vary from 1.6% to 7.2%. Moreover, some extraction time studies for both direct and headspace sampling are performed. Direct sampling shows the presence of an equilibrium condition for the carboxen/PDMS fiber, for which no extraction theory is available. Conversely, headspace sampling shows no equilibrium state; after a sampling time of one hour, the amount of EtOH extracted decreases with sampling time. This is probably due to displacement of EtOH by other compounds in the fiber.
Master of Science

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Chigome, Samuel, and Samuel Chigome. "Electrospun nanofibers : an alternative sorbent material for solid phase extraction." Thesis, Rhodes University, 2012. http://hdl.handle.net/10962/d1004972.

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The work described in the thesis seeks to lay a foundation for a better understanding of the use of electrospun nanofibers as a sorbent material. Three miniaturised electrospun nanofiber based solid phase extraction devices were fabricated. For the first two, 10 mg of electrospun polystyrene fibers were used as a sorbent bed for a micro column SPE device (8 mm bed height in a 200 μl pipette tip) and a disk (I) SPE device (5 mm 1 mm sorbent bed in a 1000 μl SPE barrel). While for the third, 4.6 mg of electrospun nylon nanofibers were used as a sorbent bed for a disk (II) SPE device, (sorbent bed consisting of 5 5 mm 350 μm stacked disks in a 500 μl SPE barrel). Corticosteroids were employed as model analytes for performance evaluation of the fabricated SPE devices. Quantitative recoveries (45.5-124.29 percent) were achieved for all SPE devices at a loading volume of 100 μl and analyte concentration of 500 ng ml-1. Three mathematical models; the Boltzmann, Weibull five parameter and the Sigmoid three parameter were employed to describe the break through profiles of each of the sorbent beds. The micro column SPE device exhibited a breakthrough volume of 1400 μl, and theoretical plates (7.98-9.1) while disk (I) SPE device exhibited 400-500 μl and 1.39-2.82 respectively. Disk (II) SPE device exhibited a breakthrough volume of 200 μl and theoretical plates 0.38-1.15. It was proposed that the formats of future electrospun nanofiber sorbent based SPE devices will be guided by mechanical strength of the polymer. The study classified electrospun polymer fibers into two as polystyrene type (relatively low mechanical strength) and nylon type (relatively high mechanical strength).

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Zimmermann, Benno F. "Proanthocyanidins in barley and malt analyzed by pressurized liquid extraction, solid-phase extraction and HPLC." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=979090113.

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Slack, Gregory C. "Coupled solid phase extraction-supercritical fluid extraction on-line gas chromatography of explosives from water." Diss., This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-05042006-164508/.

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15

Kanda, Rakesh. "Development of multi residue analytical methodology for the determination of pesticides in the aqueous environment." Thesis, University of Reading, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252240.

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Möller, Kristina. "Molecularly Imprinted Solid-Phase Extraction and Liquid Chromatography for Biological Samples." Doctoral thesis, Stockholms universitet, Institutionen för analytisk kemi, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-1042.

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This thesis focuses on the use of molecularly imprinted polymers as selective sorbents for solid-phase extraction (MISPE). The MISPE methods developed were mainly intended for use with biological samples, such as human urine and blood plasma. These body fluids are complex samples, which often need an effective clean-up step before analysis to reduce the levels of possible interfering substances from the matrix, especially if the analytes are present in trace amounts. Solid-phase extraction (SPE) is a well-established and routinely used method for clean-up and preconcentration of samples from diverse matrices. However, conventional SPE sorbents often lack selectivity, leading to co-extraction of interferences, which negatively affects the following detection method. One of the advantages of MISPE is the built-in selectivity for a target analyte, or class of structurally related analytes, enabling the efficient clean-up that is often required for biological samples. The built-in selectivity of MISPE originates from the preparation of a highly crosslinked copolymer network in the presence of an imprint molecule, i.e. the template. Subsequent removal of this template molecule leads to the creation of defined recognition sites, complementary to the shape and functionality of the template. In this work, molecularly imprinted polymers were synthesized for the first time for several types of target analytes, including diphosphate esters (Papers I-III) and a protein adduct (Paper IV) and evaluated as sorbents for solid-phase extraction. A MISPE method for extracting local anaesthetic drugs from human plasma was also evaluated (Paper V). The development of appropriate methods for using the prepared polymers to extract target analytes directly from body fluids, and the elucidation of factors that influence their performance, were major foci of all the work underlying this thesis. These are not straightforward tasks, since the recognition mechanism of the material is often based on polar interactions, which are not favoured in aqueous environments. In such cases, non-selective adsorption of the analyte(s) to the polymer surface often occurs. In order to use the MIP sorbent most effectively it is important to suppress this non-selective adsorption, without disrupting the selective adsorption of the target analyte(s) to the imprints. Generally in these studies, this strong analyte-polymer surface interaction could be repressed, and selective adsorption enhanced, by carefully optimising the conditions for washing the sorbent, in terms of organic solvent volumes, solvent polarity and the addition of an ionic modifier. The sample matrix, mainly urine, was found to strongly decrease the capacity of the MIP. Hence, this effect was further investigated. It was found that the presence of NaCl in the sample negatively affected the recovery and repeatability of the method. Furthermore, these parameters could be improved by adjusting the sample pH. It was important to control the pH of the sample, in order both to achieve selective extraction and to increase the extraction recoveries. The selectivity of MISPE for the extraction of diphosphate esters from human urine was demonstrated by comparing its performance with that of a conventional SPE sorbent, a mixed-mode-anion exchanger (MAX). Due to its efficient clean-up, MISPE generated extracts that yielded less complex ion chromatograms in subsequent LC/ESI-MS analysis than extracts from the MAX cartridge. Due to its efficient clean-up, MISPE generated extracts that yielded less complex ion chromatograms in subsequent LC/ESI-MS analysis than extracts from the MAX cartridge. Signal suppression from the interfering co-eluting compounds was detected when the MAX extracts were analysed, which was not the case for the MISPE extracts. These findings show the importance of efficient and selective sample preparation, even if a selective detector is used. Development of LC/ESI-MS methods was also an extensive component of this work (Papers I-IV). Different chromatographic conditions have been evaluated for the optimal separation and detection of the investigated compounds. Use of ion-pairing agents and suitable HPLC columns (Hypercarb and C18 Aquasil) for the acidic, polar analytes, was found to give better retention and separation than use of conventional reversed-phase columns. To improve the selectivity and detectability further, selected ion monitoring (SIM) and selected reaction monitoring (SRM) acquisition modes were used for quantification of the investigated compounds. In summary, the aim of this work was to contribute to the knowledge of the recognition mechanisms of molecularly imprinted polymers in aqueous matrices, which is important for extending the use of MISPE for several types of bioanalytical applications.

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Lee, Sukyeon. "Electrically Controlled Formation and Release of Admicelles for Solid Phase Extraction." TopSCHOLAR®, 2014. http://digitalcommons.wku.edu/theses/1334.

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Solid phase extraction is one of the most widely used methods to concentrate diluted compounds in a solution. Substances can be extracted into admicelles and hemimicelles, which are surface adsorbed micelles and surfactant monolayers, respectively. Investigations of the electrical control of surfactants on surfaces for the purpose of analyte preconcentration prior to chromatographic analysis are presented. The surfactant layer serves as the “stationary phase” in a solid phase extraction sorbent scenario. Analytes are adsorbed on this layer, and then released from the solid phase via surfactant removal. The attachment and removal of the surfactant are controlled by means of an electric field. Because the surfactant-analyte association is released by electrical control, organic solvents, which are used in conventional solid phase extraction, are not required. Therefore, this procedure is advantageous for method development and environmental concerns. Presented is the preconcentration of a test probe, 2-naphthol, using electrical control of the formation and release of dodecyl sulfate on planar gold, gold coated stainless steel, and a porous stainless steel frit, using impedance spectroscopy to observe the layer formation with various surfactant concentrations and applied potentials.

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Subrahmanyam, Sreenath. "Design of molecularly imprinted polymers for sensors and solid phase extraction." Thesis, Cranfield University, 2002. http://dspace.lib.cranfield.ac.uk/handle/1826/7576.

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This thesis presents broadly the applications of molecularly imprinted polymers in sensors and solid phase extraction. Sensors for creatine and creatinine have been reported using a novel method of rational design of molecularly imprinted polymers (MIPs), and solid phase extraction of aflatoxin-B 1 has also been described in the thesis. A method for the selective detection of creataine and creatinine is reported in this thesis, which is based on the reaction between polymerised hemithioacetal, formed by allyl mercaptan, o-phthalic aldehyde, and primary amine leading to the formation of fluorescent isoindole complex. This method was demonstrated for the detection of creatine using creatine-imprinted MIPs. Since MIPs created using traditional methods were unable to differentiate between creatine and creatinine, a new approach to the rational design of a MIP selective for creatinine was developed using computer simulation. A virtual library of functional monomers was assigned and screened against the target molecule, creatinine, using molecular modeling software. The monomers giving the highest binding score were further tested using simulated annealing in order to mimic the complexation of the functional monomers with template in the monomer mixture. The result of this simulation gave an optimised MIP composition. The computationally designed polymer demonstrated superior selectivity in comparison to the polymer prepared using traditional approach, a detection limit of 25 μM and good stability. The 'Bite-and- Switch' approach combined with molecular imprinting can be used for the design of assays and sensors, selective for amino containing substances. MEP for the selective binding properties for aflatoxin-B 1 was prepared using the computational approach. The results obtained demonstrate that the MISPE offers a simple, convenient and a rapid methodology for solid phase extraction of aflatoxin-B 1 even at very low concentrations of 2 ppb. The commercially available C-18 cartridges were able to recover only about 52% of aflatoxin-B 1 at concentrations of 2 ppb when compared with almost complete recovery by the MIP. We have proved here that, MIPs as a solid phase extraction materials offer important and practical advantages with respect to other solid phase extraction methodologies.

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Al-Saad, Jalal Abdulla. "Development of novel solid phase extraction materials for pesticide residue analysis." Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263469.

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Jabbour, Rabih Elie. "Characterization of selected immobilized metal-ions using solid phase extraction sorbents." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282773.

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Solid phase extraction (SPE) has been developed as an alternative to liquid-liquid extraction (LLE) in the sample preparation process. The advantages of SPE over LLE are that it is a more useful, reliable tool for sample preparation, which offers greater selectivity. The selectivity of an SPE sorbent is vital for the isolation of analyte from a biological matrix containing a myriad of interferences. The use of conventional ion exchange SPE for such an extraction process might not be adequate due to the adverse effects of interfering ions. Metals immobilized on various modified silicas were investigated to determine if the addition of metals improved selectivity. The selectivity of these sorbents was studied by the extraction of analytes from high ionic strength matrices. Extraction selectivity was found to depend on different factors, including the type of bonded species, metal ions used and the analytes, counter ions, sample pH and elution solvent composition. Utilizing coordination complexation between analytes and immobilized metal ions, particularly when different phases are stacked, can increase selectivity for a particular analyte. Metals immobilized by ionic exchange sorbents were observed to retain analytes of tridentate chelation capability more than immobilized metals on bonded chelators. However, bonded chelators were observed to be advantageous because they more strongly retained metal ions, relative to ionic exchangers. The interactions of immobilized silver ions with unsaturated molecules utilizing SPE were investigated. Retention of silver ions was found dependent on the nature of bonded phase. The silver ions immobilized by coordination interactions showed weaker retention than silver immobilized by ionic interactions. Retention of alkenes by silver was found to have higher flow dependence, as compared to ionic exchange or ligand exchange processes. Retention of analytes was observed to depend on a variety of factors, including the type of bonded phase used for silver immobilization, the composition of the elution solvent, steric factors, the degree of unsaturation, the geometry and position of the double bonds of the analyte molecules. Extraction selectivity for geometrical isomers decreased when silver ions were immobilized by long chain cation exchangers versus those on conventional short chain cation exchangers.

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Lang, Susann-Cathrin. "Bioavailability of HOCs in marine sediments : application of solid phase micro-extraction." Thesis, University of the West of Scotland, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.731775.

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Lee, Emma-Jane. "Forensic sample analysis using supercritical fluid extraction coupled with solid phase microextraction." Thesis, University of South Wales, 2007. https://pure.southwales.ac.uk/en/studentthesis/forensic-sample-analysis-using-supercritical-fluid-extraction-coupled-with-solid-phase-microextraction(0159ef22-bb14-433f-a50f-2bd2773ef937).html.

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A third of adults in the UK admit to using controlled substances at least once hi their lives and the most commonly abused drug was found to be cannabis, followed by the opiates and ecognine derivatives. Forensic laboratories are continually trying to reduce the turnaround time for samples submitted for analysis, to less than the current time of four days. One of the main aims of this work was to reduce the time taken to prepare, extract and analyse hair for target analytes. A new method combining supercritical fluid extraction and solid phase micro-extraction (SFE/SPME) is introduced. This coupled procedure utilises the advantages of using supercritical carbon dioxide as an extraction solvent and collecting the extract on a selected SPME fibre. Together the combined techniques provide a method that is solvent-free and highly selective, whilst reducing sample preparation to a minimum. Digested hair samples are examined by SEM to find the best method. Alkali hydrolysis and enzyme digestion using proteinase K were found to be the most effective pre-extraction methods. Solid hair samples with the addition of a derivatization reagent (BSTFA) gave the best results using the coupled technique. After optimisation and validation, the extraction from both real and spiked samples resulted in recoveries between 60% to 80% for the target analytes A9 -tetrahydrocannabinol (A9- THC) , cannabinol (CBN) and cannabidiol (CBD). Other forensic applications such as the extraction of polycyclic aromatic hydrocarbons and pesticides from environmental and food samples and the examination of fire debris for the presence of accelerants are also carried out. PAH could easily be extracted from complex matrices to give recoveries of up to 97% for some analytes at the optimized conditions of 90°C at 4500 psi over a 10 minute dynamic extraction period. Pesticide extraction gave recoveries of 60 - 80% while the extraction of accelerants from fire debris clearly showed that accelerants such as diesel can be identified over the coincidental PAH and hydrocarbon peaks found in burnt debris. The coupling of SFE to SPME provides an exciting technique that has a wide range of applications and creates potential for a fully automated on-line system.

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Gulamussen, Noor Jehan. "Electrospun sorbents for solid phase extraction (SPE) and colorimetric detection of pesticides." Thesis, Rhodes University, 2014. http://hdl.handle.net/10962/d1013241.

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The thesis presents the evaluation of polysulfone sorbents for solid phase extraction (SPE) and the development of colorimetric probes for pesticides analysis in water. Through electrospraying and electrospinning techniques, different morphologies of sorbents (particles, beaded fibers and bead-free fibers) were fabricated. The sorbents were morphologically characterized by scanning electron microscopy. Adsorption capacities of sorbents were evaluated by conducting recoveries studies for model pesticides; atrazine, chlorpyrifos and DDT using batch and column SPE modes. Better recovery results were achieved by employing the batch mode of fibers, as values ranged from 98 to 105percent. Further sorbent evaluation was conducted using breakthrough experiments and static experiments. The breakthrough studies indicated that 1700 μL was the sample volume that could be percolated with no breakthrough of the analyte that correspond to a concentration of 150 mg/g of sorbent that can be extracted without any loss of analyte. From static studies, quantities of each model compound adsorbed into the fiber at the equilibrium time were evaluated. The adsorbed atrazine was 65, chlorpyrifos 250 and DDT 400 mg/g of sorbent. Kinetic studies suggested retention mechanism following pseudo first and second order model observed by high correlation coefficients (> 0. 96), demonstrating the fiber affinity to retain both polar and non-polar compounds opening a possibility to be used as sorbent for sample preparation of different classes of pesticides in water. For the second part of the study simple strategies for colorimetric sensing based on silver nanoparticles and polivinylpyrrolidone capped nanoparticles were developed, respectively for atrazine and chlorpyrifos detection. The limits of detection of the methods were 3.32 and 0.88 mg/L for atrazine and chlorpyrifos respectively. The applicability of the probe in real samples was demonstrated by the recoveries studies of tap water varying from 94 to 104 percent. The versatility of the probe was demonstrated by affording a simple, rapid and selective detection of atrazine and chlorpyrifos in the presence of other pesticides by direct analysis without employing any sample handling steps. Attempt to incorporate the probes in a solid support was achieved by using nylon 6 as solid support polymer proving to be fast and useful for on-site detection.

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Sexton, Diane Lynne. "Analysis of disinfection by products in drinking water by solid phase extraction." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-09122009-040321/.

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25

Bristow, Anthony Walter Thomas. "Laser desorption and high resolution studies in quadrupole ion trap mass spectrometry." Thesis, Nottingham Trent University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336973.

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26

Kremser, Andreas [Verfasser], and Torsten Claus [Akademischer Betreuer] Schmidt. "Advances in automated sample preparation for gas chromatography : solid-phase microextraction, headspace-analysis, solid-phase extraction / Andreas Kremser ; Betreuer: Torsten Claus Schmidt." Duisburg, 2016. http://d-nb.info/1116941864/34.

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27

Möller, Kristina. "Molecularly imprinted solid-phase extraction and liquid chromatography/mass spectrometry for biological samples /." Stockholm : Department of Analytical Chemistry, Stockholm University, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-1042.

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Martin, Paul D. "The application of molecular imprinted polymers to the solid phase extraction of drugs." Thesis, Keele University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250426.

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Molecular imprinted polymers (MIPs), prepared to propranolol, were evaluated as solid phase extraction (SPE) phases. Monolithic MIPs were converted to particulate SPE materials by crushing, sieving, and sedimentation to remove fines. A high proportion (85%) of template propranolol was recovered with initial washes of the MIPs. Template leaching diminished with successive washes though low level leachings till compromised analysis of propranolol at trace levels (<5ng/mL). It was possible to retain propranolol on the MIPs following application in aqueous solution, biological matrices and organic solvent. In reversed and normal phase mode it was necessary to include an acid or base to achieve elution of basic compounds. In reversed phase mode, propranolol-imprinted MPs showed a degree of selectivity when using methanol:water:triethylamine but not methanol:water:trifluoroacetic acid elution solvents. This selectivity was related to structure when structurally-diverse compounds were assessed. Selectivity was very limited when assessed using compounds structurally similar to propranolol. In normal phase mode, MIPs retained amino-alcohols more strongly than a non-imprinted polymer though there was no evidence of a structure-related selectivity. A non-imprinted polymer and one prepared to an alternative template (tamoxifen) were assessed as reference polymers by which to assess the selectivity of propranolol-imprinted MIPs. Both materials were suitable references in reversed-phase mode though little selectivity was evident. The non-imprinted polymer was a poor comparator in normal phase mode as it appeared to show lesser non-specific binding than the imprinted MIP. Reversed and normal phase SPE methods were successfully developed for compounds structurally-simila to propranolol from human plasma. A protein precipitation step ahead of SPE was necessary. The MEP-based asays showed no advantage over conventional SPE and solvent extraction assay approaches. Although MIP-based extracts were clean, accuracy was poor at low concentrations (2 and 5 ng/mL) due to interference from template impurities leaching from the MJP.

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29

Cooper, Gail Audrey Ann. "Application of solid-phase extraction for the analysis of drugs in biological matrices." Thesis, University of Glasgow, 1999. http://theses.gla.ac.uk/5368/.

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Experimental mixed-mode solid-phase extraction columns of differing carbon number and carbon loading were investigated for the efficient extraction of drugs of abuse from biological matrices. Methadone and its two major metabolites (EDDP and EMDP) were chosen due to the increase in methadone drug-related deaths in the West of Scotland. Amphetamine and related compounds (methamphetamine, 3,4-methylenedioxyamphetamine (MDA), 3,4-methyleneidoxymethamphetamine (MDMA) and 3,4-methylenedioxyethylamphetamine (MDEA)) were chosen because of the prevalence of use of "speed" and "ecstasy" throughout the United Kingdom and the challenge these volatile drugs pose to the analyst. Improved methods were developed for the efficient extraction of methadone, EDDP and EMDP from whole blood and for amphetamine and related compounds from whole blood and hair. These methods were successfully applied to the analysis of postmortem samples. The stability of methadone, EDDP and EMDP in whole blood was investigated using the developed extraction method after sorting at various temperatures for a period of six months. Methadone remained stable in blood after six months. This was confirmed by the analysis of postmortem cases samples which when re-analysed within six months of the initial analysis, correlated well. Postmortem hair samples proved useful for determining antecedent drug use history whether extracted by solid-phase extraction or after screening with a Cohort enzyme immunoassay kit, adapted for hair analysis. Solid-phase extraction provides a clean and efficient means of extracting drugs of abuse from whole blood and hair. Simple manipulation of the extraction system (sample pretreatment, pH, derivatisation) provides a versatile alternative to lengthy liquid-liquid extraction techniques and has the added potential of automation.

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30

Tancu, Yolanda. "Electrospun nanofibers as solid phase extraction sorbents and support for alkylphenols colorimetric probes." Thesis, Rhodes University, 2014. http://hdl.handle.net/10962/d1012997.

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The thesis reports on fabricating alternative solid phase extraction (SPE) sorbents and colorimetric probes based on electrospun nanofibers for alkylphenols (APs). Hydroxyl methylated styrene [poly(co-styrene-CH₃OH)] and 3-oxobutanoate styrene [poly(co-styrene-OCOCH₃COCH₃)] copolymers were synthesized and fabricated into sorbent materials by electro-spinning/spraying. The fabricated morphologies consisting of bead free fibers, beaded fibers and particles were evaluated as SPE sorbents using batch experiments. Electropun fibers proved to be better sorbents as they exhibited extraction efficiency that exceeded 95% compared to 60% for beaded fibers and 40% for particles. In view to reduce sample and solvent volumes, smooth fibers were packed into pipette tips as SPE devices that yielded quantitative recoveries of APs from spiked wastewater samples. Recoveries ranged from 70% to 125% with LOD of 0.008, 0.01 and 0.1 μg mL⁻¹ for 4-tert octylphenol (4-t-OP), 4-octylphenol (4-OP) and 4-nonylphenol (4-NP) respectively, when using high performance liquid chromatography-fluorescence detector (HPLC-FLD). Furthermore, amino functionalised polydiacetylene polymers (PDAs), citrate capped gold (AuNPs) and silver nanoparticles (AgNPs) were evaluated as colorimetric probes for visual detection of APs. In colloidal studies, AuNPs probe showed a colour change from wine red to green upon introduction of analyte. UV-vis spectroscopy revealed the shifting of the surface plasmon resonance (SPR) peak from 525 nm to 729 nm induced by aggregation of AuNPs. For AgNPs probe, a colour change was observed from yellowish green to brown. Transmission electron microscopy (TEM) studies showed growth of AgNPs. A presumed oxidation of the analyte, forming an absorbing compound at 279 nm in both AgNPs and PDAs probes was also observed. For PDAs probe the colour change was from purple to pink. Concentrations as low as 30 μg mL⁻¹ were detectable in all colloidal based probes. Further colorimetric investigations were conducted with electrospun AuNPs-nylon 6 fiber mat. A colour change from purplish red to navy blue at concentrations of 1000 μg mL⁻¹ was observed. Electrospun AgNPs –nylon 6 fiber mat did not show a distinct colour change. High resolution scanning electron microscopy (HRSEM) revealed the analyte inducing the assembly of AuNPs and AgNPs as they covered the surface of the nanofiber mat. Electrospun nanofibers are a platform for analysis and thus tuning their chemistry will lead to sensitive and selective methods

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Dilley, Katherine. "Optimising silica-based solid phase DNA extraction methods for low concentration forensic samples." Thesis, Dilley, Katherine (2019) Optimising silica-based solid phase DNA extraction methods for low concentration forensic samples. Masters by Coursework thesis, Murdoch University, 2019. https://researchrepository.murdoch.edu.au/id/eprint/48187/.

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Trace DNA analysis from minute biological samples has become commonplace in modern forensic laboratories due to increased sensitivities in genotyping systems and improved extraction chemistries. However, analysis still remains a challenge as no single protocol exists that will isolate DNA in both sufficient quantity and quality for downstream applications. Extraction is the most crucial step for maximising recovery of DNA, and thorough optimisation of procedures is needed to ensure informative genetic profiles can be generated. This review will investigate the efficiency of different methods available for isolating trace quantities of DNA from forensic samples, discussing their advantages and limitations. It will explore improvements to the extraction methodology, including optimisation of the elution volume and methods of post-extraction purification. Lastly, centrifugal filters will be debated for their concentrating properties and ability to improve the recovery of trace DNA.

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32

Mann, Thierry Dominic. "Factors affecting the selectivity and efficiency of solid phase extraction of ionizable compounds." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282287.

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Solid phase extraction (SPE) is an extension of conventional liquid chromatographic methods. In the case of SPE the desired separation is digital in nature. Under one solvent condition total retention occurs while under a second solvent condition total elution occurs. The role of SPE as a sample preparation tool is becoming more dominant in the field of analytical chemistry. The need for high throughput, decreased solvent usage, and automation makes SPE the method of choice over other extraction methods. Ionic interactions at modified silica sorbents are studied with respect to the impact on the isolation and purification of analytes. The interactions are characterized by quantitating absolute recoveries for a variety of analytes under different conditions, and qualitative analysis of analytical interferences. Extractions of ionizable compounds were found to be dependent on a myriad of factors. These factors include sample pH, buffer composition, solution concentration, and elution solvent composition. Selectivities for ionizable analytes can be increased by utilizing ionic interactions, particularly in a mixed-mode operation. The extraction of basic compound compounds is generally robust, while methods for the acidic analytes are more highly dependent on the type of counter-ion. Ion selectivities observed were different than those recorded for polymer-based ion-exchange sorbents. The organization of water in the near surface region of the silica-based sorbents is the reason for the disparity between the two types of materials. The utility of a polymeric polystyrene divinylbenzene sorbent for the analysis of analytes from biological matrices is demonstrated. It was shown that these sorbents can withstand harsh chemical environments that would preclude using a silica-based material. Analysis times were shortened and extraction efficiencies were comparable to the silica materials. The extractions were not as selective as those performed on mixed-mode sorbents however.

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33

Zimmermann, Benno F. [Verfasser]. "Proanthocyanidins in barley and malt analyzed by pressurized liquid extraction, solid-phase extraction and HPLC / Benno F Zimmermann." Aachen : Shaker, 2005. http://d-nb.info/979090113/34.

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34

Giardina, Matthew. "THE DEVELOPMENT AND CHARACTERIZATION OF LOW-TEMPERATURE GLASSY CARBON FILMS FOR SOLID PHASE MICROEXTRACTION." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1037839211.

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35

Nuntawong, Nuchnipa. "Comparative study of pyrrolizidine alkaloids in Heliotropium indicum, H. amplexicaule and H. arborescens." Thesis, Liverpool John Moores University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343131.

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36

Mills, Malcolm John. "Effective use of microbore LC with peak compression for the analysis of drugs in biological fluids." Thesis, University of Sunderland, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297131.

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37

Amini, Nahid. "Novel Solid Phase Extraction and Mass Spectrometry Approaches to Multicomponent Analyses in Complex Matrices." Doctoral thesis, Stockholms universitet, Institutionen för analytisk kemi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-38625.

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Analysis of compounds present in complex matrices is always a challenge, which can be partly overcome by applying various sample preparation techniques prior to detection. Ideally, the extraction techniques should be as selective as possible, to minimize the concentration of interfering substances. In addition, results can be improved by efficient chromatographic separation of the sample components. The elimination of interfering substances is especially important when utilizing mass spectrometry (MS) as a detection technique since they influence the ionization yields. It is also important to optimize ionization methods in order to minimize detection limits. In the work this thesis is based upon, selective solid phase extraction (SPE) materials, a restricted access material (RAM) and graphitized carbon black (GCB) were employed for clean up and/or pre-concentration of analytes in plasma, urine and agricultural drainage water prior to liquid chromatography/mass spectrometry (LC/MS). Two SPE formats, in which GCB was incorporated in µ-traps and disks, were developed for cleaning up small and large volume samples, respectively. In addition, techniques based on use of sub-2 µm C18 particles at elevated temperatures and a linear ion trap (LIT) mass spectrometer were developed to improve the efficiency of LC separation and sensitivity of detection of 6-formylindolo[3,2-b]carbazole (FICZ) metabolites in human urine. It was also found that GCB can serve not only as a SPE sorbent, but also as a valuable surface for surface-assisted laser desorption ionization (SALDI) of small molecules. The dual functionality of GCB was utilized in a combined screening-identification/quantification procedure for fast elimination of negative samples. This may be particularly useful when processing large numbers of samples. SALDI analyses of small molecules was further investigated and improved by employing two kinds of new surfaces: oxidized GCB nanoparticles and silicon nitride.

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38

Pickering, Kali R. "Admicelle-Based Solid Phase Extraction of Phenols Using Dialkylammonium Surfactant in the Hydroxide Form." TopSCHOLAR®, 2008. http://digitalcommons.wku.edu/theses/15.

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A technique for admicelle-based solid phase extraction is presented in which a dialkylammonium surfactant in the hydroxide form is immobilized on silica. By converting dihexadecyldimethylammonium bromide to the hydroxide form, the surfactant is allowed to have the property of a strong base, aiding in the extraction of acidic phenols which are difficult to extract because of their differing polarities. The surfactant-silica admicelle parameters were optimized for the efficient extraction of eight phenols. Adsorbed phenols were eluted from the sorbent using small volumes of methanol. The phenols were preconcentrated from drinking water samples and were determined using high performance liquid chromatography (HPLC) coupled with a photo diode-array detector.

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39

Khdary, Nezar Hassan Mohammed. "Silica based nanoscavengers for the determination of environmental pollutants using solid phase dispersion extraction." Thesis, University of Southampton, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484969.

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The presence of toxic metals and organic substances in environmental waters has serious implications for human health. The extraction and pre-concentration of these substances from 'ater samples is a core component of their determination. 'Ibis thesis introduces newly developed nanoscavengers for the extraction and pre-concentration.of harmful substances - om water samples~ using a new s,olid phase dispersion extraction technique (SPDE). This technique is based on the dispersion of 250 nm diameter, mqdified silica particles (nanoscavengers) in water samples, to extract the analytes. Uniform silica particles were synthesised by both a conventional sol-gel process and a new spray technique. The parameters influencing their formation were investigated, and it was found that the concentration of tetraethoxysilane (TEOS), ammonia, solvent, temperature and agitation, can all affect the final particle size. The silica particles were characterized by scanning electron microscopy (SEM) and particle size analysis. Under optimal conditions, very uniform and monodisperse silica spherical particles, having the target diameter of 250 nm 8 nm), were obtained. Different types of nanoscavenger were synthesised by modification of the silica with a number of silane coupling agents, such as N-[3-(trimethoxysilyl)propyl]-ethylenediamine and its dithiocarbamate, 3-mercaptopropyltrimethoxysilane, octadecyltrichlorosilane and octadecyltrimethoxysilane. The modification step was carried out by two different processes: the modification of pre-formed 250 nm silica particles and by a single-pot synthesis. Both processes showed a successful immobilization of silylating agents with a variation of loading. The amino-nanoscavenger, when applied to the pre-concentration of copper from water gave a recovery of 98%. A dithiocarbamate-nanoscavenger was applied to the preconcentration of cadmium, copper~ lead and nickel and recoveries were 99, 97, and 92%, respectively. Inorganic mercury and arsenic were pre-concentrated using a mercaptonanoscavenger, and recoveries of 106 and 96% were obtained, respectively. The collection of organic species using the C1S-nanoscavenger resulted in the recovery of 70% di-n-butyl phthalate. Herbicides such as Atrazine, Ramrod, Diuran and Propazine were recovered efficiencies of 66, 78, 82 and 59%, respectively. A dual-functionalitynanoscavenger was employed for the pre-concentration of 22 chlorinated pesticides, and recoveries varied from 70 to 100%. Polynuclear aromatic hydrocarbons (PAHs) were also pre-eoncentrated from water samples using this dual-functionality-nanoscavenger, and recoveries of 13 PARs varied from 70 to Nanoscavenger based solid phase dispersion extraction 'SPDE' offers many advantages over conventional approaches. These include the minimization of regents, transportability, field application and efficiency.

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40

Asri, Kamarruddin. "Solid phase extraction techniques for the analysis of pesticides and drugs in biological specimens." Thesis, University of Glasgow, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249939.

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41

Green, Caroline Elizabeth. "An experimental and modelling investigation into the solid-phase extraction of pollutants from water." Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322408.

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42

Croxtall, Ben. "The application of solid phase extraction in organic synthesis using fluorous derivatised metal catalysts." Thesis, University of Leicester, 2003. http://hdl.handle.net/2381/30076.

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This thesis describes the synthesis, characterisation and coordination chemistry of a variety of fluorinated ÃŸ-diketonate ligands (I) and carboxylate ligands (II), the catalytic activity of the resultant metal complexes for oxidation and C-C bond forming reactions, and an evaluation of fluorous methodologies for catalyst/product separation. (Fig. 3706) Chapter 1 introduces the concept and application of fluorous methodologies, including fluorous biphase catalysis and fluorous reverse phase silica gel (FRPSG), as alternative approaches to product/catalyst separation in homogeneous catalysis. Chapter 2 describes the synthesis and characterisation, in some cases by X-ray diffraction, of the fluorinated ÃŸ-diketonate ligands and an evaluation of the influence of the perfluoroalkyl groups on the coordination of these ligands to a variety of transition metals including copper, nickel, palladium and zinc. Chapter 3 outlines attempts to sue fluorous nickel ÃŸ-diketonate complexes for the oxidation of sulfides. The results indicate that a metal catalyst is not necessary for oxidation in this system although the veracity of catalyst separation using FRPSG was established. This chapter also describes the investigation of a fluorous molybdenum ÃŸ-diketonate complex for the oxidation of alkenes, although the extreme moisture senstiviity of the complex negated any attempts at recovery and recycling. The scope of Lewis acid catalysed coupling of ÃŸ-diketones with cyanoformates and the ability to reuse and recycle the fluorinated ÃŸ-diketonate catalysts is described in chapter 4. Chapter 5 describes attempts to extend this efficient separation procedure to the C-C bond forming reactions of rhodium carboxylate dimers. Although catalysis was observed, catalyst/product separation using FRPSG was unsuccessful. Chapter 6 summarises all the experimental details and spectroscopic data, whilst a CD-rom includes all of the crystallographic data.

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43

Quintana, Jorge E. "Preparation of an Immunosorbent and its use in the Solid Phase Extraction of Benzodiazepines." FIU Digital Commons, 2012. http://digitalcommons.fiu.edu/etd/758.

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The use of capillary electrophoresis (CE) has been restricted to applications having high sample concentrations because of its low sensitivity caused by small injection volumes and, when ultraviolet (UV) detection is used, the short optical path length. Sensitivity in CE can be improved by using more sensitive detection systems, or by preconcentration techniques which are based on chromatographic and/or electrophoretic principles. One of the promising strategies to improve sensitivity is solid phase extraction (SPE). Solid Phase Extraction utilizes high sample volumes and a variety of complex matrixes to facilitate trace detection. To increase the specificity of the SPE a selective solid phase must be chosen. Immunosorbents, which are a combination of an antibody and a solid support, have proven to be an excellent option because of high selectivity of the antibody. This thesis is an exploratory study of the application of immunosorbent-SPE combined with CE for trace concentration of benzodiazepines. This research describes the immobilization and performance evaluation of an immunosorbent prepared by immobilizing a benzodiazepine-specific antibody on aminopropyl silica. The binding capacity of the immunosorbent, measured as µg of benzodiazepine/ gram of immunosorbent, was 39 ± 10. The long term stability of the prepared immunosorbent has been improved by capping the remaining aminopropyl groups by reaction with acetic anhydride. The capped immunosorbent retained its binding capacity after several uses.

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44

Simmons, Steven Tyler. "Commercial Applicability of an Innovative Anthocyanin Purification Technique, Utilizing Mixed-Mode Solid-Phase Extraction." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1332267706.

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45

CEYLAN, OZCAN. "ELECTROCHEMICALLY-AIDED CONTROL OF SOLID PHASE MICRO-EXTRACTION (EASPME) USING CONDUCTING POLYMER COATED FIBER." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1069853643.

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46

Bellu, Edmund. "Detection, analysis, and photocatalytic destruction of the freshwater taint compound geosmin." Thesis, Robert Gordon University, 2007. http://hdl.handle.net/10059/93.

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A significant issue affecting the aquaculture and water industries is the presence of off-flavour compounds in water, which cause problems by imparting an undesirable earthy/musty flavour and smell to water and fish. Two predominant off-flavour compounds are geosmin (GSM) and 2-methylisoborneol (MIB). These compounds are produced by several varieties of cyanobacteria and actinomycetes as metabolic products and can be detected by humans at concentrations as low as 0.015 mg L-1. Removal of GSM and MIB from potable waters has proven to be inefficient using standard water treatment such as filtration, coagulation, flocculation, sedimentation and chlorination. Activated carbon and membrane processes can physically remove GSM and MIB, but do not destroy them, and ozone treatment can be expensive. Titanium dioxide (TiO2) photocatalysis has recently been demonstrated to rapidly degrade GSM and MIB. When the semiconductor catalyst is illuminated with ultraviolet light simultaneous oxidation and reduction reactions occur. Pollutants are broken down into mineral acids, carbon dioxide and water. This study was conducted to determine if TiO2 photocatalysis, using a pelleted form of TiO2 called Hombikat K01/C, was a suitable method for the treatment of potable water. Additionally an analytical method was developed to rapidily analyse the large number of samples generated. Two reactors, a bench scale batch reactor and pilot scale flow reactor, were developed and used to evaluate the efficacy of Hombikat K01/C TiO2 photocatalysis in degrading GSM. The batch reactor, containing Hombikat K01/C, was used to investigate the effect of numerous experimental variables on the photocatalysis of GSM, including initial substrate concentration, pH, light intensity, aeration rate, the presence of additional reactants, and catalysis conducted in deuterated water. GSM was rapidly degraded using the TiO2 batch reactor, with the rate of GSM degradation most affected by light intensity and additional reactants, though pH also had a notable effect. A kinetic isotope effect of 1.61 was observed for the destruction of GSM using Hombikat K01/C TiO2. The flow reactor was also found to efficiently degrade GSM in raw waters. The rate of GSM destruction was found to be significantly lowered by UV shielding of the catalyst, caused by constituents of raw the water used, and the presence of additional reactants. The pilot scale flow reactor was also successfully evaluated in Denmark using gesomin contaminated water from an eel farm

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47

Sheehan, Emily Moore. "Time-weighted average solid-phase microextraction (TWA-SPME) for in-planta detection of chlorinated solvents." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2009. http://scholarsmine.mst.edu/thesis/pdf/Sheehan_09007dcc8067c9a4.pdf.

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Thesis (M.S.)--Missouri University of Science and Technology, 2009.
Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed June 16, 2009). Includes bibliographical references (p. 63-66).

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48

Blankenship, Donna A. "Evaluation of SPEC®•Microcolumns for the extraction of ranitidine from urine." Thesis, Virginia Tech, 1994. http://hdl.handle.net/10919/44600.

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Menon, Sreejit Rajiv Menon. "Design and Development of 2-Functionalized Calix[4]arenes and Their Investigation in the Separation of Lanthanides." University of Toledo / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1461715995.

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50

Gröning, Mikael. "Solid-Phase Microextraction in Polymer Analysis - Extraction of Volatiles from Virgin and Recycled Polyamide 6.6." Doctoral thesis, KTH, Fibre and Polymer Technology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-60.

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The extraction and quantitative analysis of low molar mass compounds in polymers is an analytical challenge. It is also important from a practical point of view because the low molar mass compounds in time will migrate from the polymers into the surrounding environment. It is especially important to gain knowledge about the migrating compounds in applications such as medical implants, packaging materials and car interiors. The main aim of this thesis was to develop headspace solid phase microextraction (HS-SPME) methods to meet this challenge. In addition, the work aimed to show the applicability of the methods developed in quality control of polymers, degradation studies and assessment of polymer durability.

Factors influencing the extraction of low molar mass compounds from polyamide 6.6 were studied. Particular attention was paid to the matrix effects and to the establishment of headspace equilibrium of 2-cyclopentyl-cyclopentanone in solid polyamide. Hydrogen bonding and adsorption of analyte to the polar matrix was observed and found to cause exceedingly slow establishment of equilibrium. The adsorption could be eliminated by the addition of water, which replaced 2-cyclopentyl-cyclopentanone at the adsorption sites of the polyamide and made it possible to measure the 2-cyclopentyl-cyclopentanone content in polyamide 6.6 using multiple headspace solid-phase microextraction (MHS-SPME).

A correlation between the emitted amount of 2-cyclopentyl-cyclopentanone and the amount 2-cyclopentyl-cyclopentanone in the material was found. The correlation was valid also under non-equilibrium conditions, which allows rapid assessment of the 2-cyclopentyl-cyclopentanone content in polyamide 6.6 using headspace sampling.

20 different low molar mass compounds were identified in virgin and recycled polyamide 6.6. The compounds could be classified into four groups: cyclic imides, pyridines, chain fragments and cyclopentanones. The structures of the degradation products imply that the thermo-oxidative degradation starts at the N-vicinal methyl group. Larger amounts of degradation products at lower degree of degradation were formed in recycled than in virgin polyamide 6.6. Thus, processing increases the susceptibility of polyamide 6.6 to thermal oxidation. The total amount of cyclopentanones was reduced upon processing and oxidation. Cyclopentanones are thus not thermo-oxidation products of polyamide 6.6. N-pentyl-succinimide showed the most significant increase due to oxidation and processing. The formation of N-pentyl-succinimide was in correlation with the simultaneous changes in tensile strength. The largest increase in N-pentyl-succinimide coincided with the largest drop in tensile strength.

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