Log in

Relevant bibliographies by topics / HPLC (high-performance liquid chromatography) / Dissertations / Theses

To see the other types of publications on this topic, follow the link: HPLC (high-performance liquid chromatography).

Dissertations / Theses on the topic 'HPLC (high-performance liquid chromatography)'

Author: Grafiati

Published: 4 June 2021

Last updated: 9 February 2022

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 dissertations / theses for your research on the topic 'HPLC (high-performance liquid chromatography).'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.

1

Benson, Andrew James. "High-performance liquid chromatography (HPLC) and high-performance liquid chromatography mass spectrometry (HPLC/MS) for the analysis of date rape drugs." FIU Digital Commons, 2002. http://digitalcommons.fiu.edu/etd/1602.

Full text

Abstract:

The drugs studied in this work have been reportedly used to commit drug-facilitated sexual assault (DFSA), commonly known as "date rape". Detection of the drugs was performed using high-performance liquid chromatography with ultraviolet detection (HPLC/UV) and identified with high performance-liquid chromatography mass spectrometry (HPLC/MS) using selected ion monitoring (SIM). The objective of this study was to develop a single HPLC method for the simultaneous detection, identification and quantitation of these drugs. The following drugs were simultaneously analyzed: Gamma-hydroxybutyrate (GHB), scopolamine, lysergic acid diethylamide, ketamine, flunitrazepam, and diphenhydramine. The results showed increased sensitivity with electrospray (ES) ionization versus atmospheric pressure chemical ionization (APCI) using HPLC/MS. HPLC/ES/MS was approximately six times more sensitive than HPLC/APCI/MS and about fifty times more sensitive than HPLC/UV. A limit of detection (LOD) of 100 ppb was achieved for drug analysis using this method. The average linear regression coefficient of correlation squared (r2) was 0.933 for HPLC/UV and 0.998 for HPLC/ES/MS. The detection limits achieved by this method allowed for the detection of drug dosages used in beverage tampering. This method can be used to screen beverages suspected of drug tampering. The results of this study demonstrated that solid phase microextraction (SPME) did not improve sensitivity as an extraction technique when compared to direct injections of the drug standards.

APA, Harvard, Vancouver, ISO, and other styles

2

Edwardson, P. A. D. "High Performance Liquid Chromatography of polynucleotides and proteins." Thesis, London School of Hygiene and Tropical Medicine (University of London), 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376534.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Forssén, Patrik. "Adsorption isotherm parameter estimation in nonlinear liquid chromatography /." Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5971.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

DONALD, GREGORY THOMAS. "Model Chiral Ionic Liquids for High Performance Liquid Chromatography Stationary Phases." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1214325450.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Ritchie, Harald John. "Development of new packing materials for high performance liquid chromatography." Thesis, University of Edinburgh, 1987. http://hdl.handle.net/1842/14283.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Scholtzova, Angela. "Scale up and modelling of HPLC." Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368109.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Walker, Roderick Bryan. "HPLC analysis and pharmacokinetics of cyclizine." Thesis, Rhodes University, 1995. http://hdl.handle.net/10962/d1003279.

Full text

Abstract:

The investigations detailed in this dissertation have been conducted to address the paucity of pharmacokinetic information, in published literature, pertaining to cyclizine. The areas of investigation have included the selective quantitation of both cyclizine and its demethylated metabolite, norcyclizine in serum and urine, assessment of stability of both compounds in stored biological samples, dosage form analysis, dissolution rate testing of tablets, and bioavailability and pharmacokinetics following administration of an intravenous solution, and tablets to humans. High-performance liquid chromatography (HPLC) was used as the main analytical technique throughout these studies. An original HPLC method employing ultraviolet detection with a limit of quantitation of 5μg/ℓ was developed for the determination of cyclizine in serum and both cyclizine and norcyclizine in urine, Solid-phase extraction using extraction columns packed with reversed-phase C18 material, and followed by a simple phase-separation step proved successful for the accurate and precise isolation of the compounds. The validated method was applied to the analysis of serum and urine samples from a pilot study in which a single volunteer was administered 50mg of cyclizine hydrochloride. Several samples collected during the pilot study revealed the presence of both drug and metabolite in concentrations below the limit of detection. In order to improve the selectivity and sensitivity of the analytical method an HPLC method with electrochemical detection operating in the "oxidative-screen" mode was developed. The solid-phase extraction procedure was modified slightly and the method found to be precise, accurate, selective and highly sensitive with a limit of quantitation of Iμg/g/l for both cyclizine and norcyclizine in both serum and urine. This method was applied to the determination of both compounds after intravenous and oral administration of cyclizine to humans. HPLC with electrochemical detection was used for the analysis of samples collected during dissolution studies on the batch of tablets used for pharmacokinetic studies. In addition, this method was used to assess content uniformity of the tablets and of samples from the batch of intravenous ampoules of cyclizine lactate. Dissolution studies showed that all tablets tested passed the compendial specifications for cyclizine. Content uniformity assessment revealed that within-batch uniformity existed for both the tablets and ampoules and, therefore, variations in pharmacokinetic parameters for the drug would more than likely be as a result of inter- and intra-individual variability within the subject population. Pharmacokinetic information for cyclizine was obtained following administration of an intravenous bolus dose of cyclizine lactate as a solution, oral administration of cyclizine hydrochloride as a single dose of 50mg and as fixed multiple doses of 50mg every 8 hours for five days. Further information was acquired following administration of single doses of 100mg and 150mg cyclizine hydrochloride. Data collected from these studies were evaluated using both compartmental and non-compartmental techniques. Cyclizine was rapidly absorbed following oral administration with mean kₐ = 1.54 hr⁻¹ and was found to have an absolute bioavailability (F) of 0.47. The presence of norcyclizine in serum following oral and not intravenous dosing suggests cyclizine is susceptible to "first-pass" metabolism in either the gut wall or the I iver. Mean ClTOT determined following the intravenous dose was 0.865 ℓ/hr/kg. The mean ClTOT of 0.823 ℓ/hr/kg calculated following oral dosing, using a unique value of F for each subject compared favourahly with that obtained following intravenous dosing. Renal clearance of cyclizine is negligihle indicating that non-renal routes of elimination account for the majority of removal of cyclizine form the body. Cyclizine is extensively distributed and the mean Vz following an intravenous dose was 16.70 ℓ/kg. This value is lower than that calculated from all oral studies from which the mean Vz was determined to be 25.74 ℓ/kg. Cyclizine is eliminated slowly with a mean elimination t½ = 20.11 hours. Cyclizine dose not appear to follow dosedependent kinetics and therefore, inability to predict steady state levels are more than likely due to accumulation as a result of frequent dosing rather than saturation of elimination mechanisms. Modelling of intravenous data to one-compartment (lBCM), two-compartment (2BCM) and threecompartment models indicated that the pharmacokinetics of cyclizine can be adequately described by a 3BCM. The drug is rapidly distributed into a "shallow" peripheral compartment (α = 9.44 hr⁻¹ , and k₂₁ = 2.09 hr⁻¹ ), and slowly distributed to the "deep" peripheral compartment (β = 0.451 hr⁻¹ and k₃₁ = 0.120 hr⁻¹ ). Modelling of all oral data indicated that a 2BCM best described the pharmacokinetics of the drug, however, distribution to the peripheral compartment is not as rapid as to the "shallow" peripheral compartment following the intravenous dose. Mean distribution parameters were α = 0.64 hr⁻¹1 and, k₂₁ = 0.39 hr⁻¹. Mean CITOT following intravenous dosing of 0.70 ℓ/hr/kg was similar to the mean CIToT of 0.73 ℓ/hr/kg determined after oral dosing. The mean distribution volume at steady state determined following intravenous dosing (17.78 ℓ/kg) was lower than that obtained from the oral studies (25.52 ℓ/kg). The mean terminal elimination half-lives calculated for cyclizine following fitting of intravenous and oral data was 25.09 hours. In general, mean pharmacokinetic parameters calculated following titting of data to a 2BCM after oral administration correlate closely with those calculated using non-compartmental techniques. However, the pharmacokinetics following intravenous dosing are better described by a 3BCM and a close correlation between parameters estimated using noncompartmental techniques and compartmental techniques is evident when a 3BCM model is used.

APA, Harvard, Vancouver, ISO, and other styles

8

Narine, Raymond. "A novel microcomputer-controlled transport detector for high-performance liquid chromatography." Thesis, King's College London (University of London), 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281718.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Lowe, Christian T. "Retention characteristics of water-soluable calixarene modified mobile phases in HPLC /." Connect to the full text of the document, 1998. http://www.ohiolink.edu/etd/view.cgi?ysu997550028.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Li, F. "Studies of haem biosynthesis and metabolism by high-performance liquid chromatography." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378943.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Watson, Richard Charles. "Studies of reversed phase high performance liquid chromatography (RP-HPLC) stationary phases." Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338492.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Trusova, Tatyana. "Quantitative estimation of bile acid conjugates in human bile using HPLC /." Connect to online version, 1995. http://hdl.handle.net/1989/3555.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Weddle, Carolyn A. "Optimization of HPLC techniques for separation of oxidized phosphatidylcholines." Virtual Press, 2005. http://liblink.bsu.edu/uhtbin/catkey/1319835.

Full text

Abstract:

In cellular studies of patients with lipid related disorders such as mammary cancers, leukemia, and artheroscierosis, separation of molecular species of oxidized phosphatidylcholine (PC) can be an important assistance in research or diagnosis. Goals of this project were to optimize separation of oxidized and unoxidized PC molecular species in a single HPLC chromatogram followed by in line identification of hydroperoxides. Oxidized egg PC's were produced using UV light exposure in air. Separations were performed on an Ultrasphere ODS column and an Asahipak ODPVA column using a Waters 2695 system with photodiode array. The ODPVA column routinely gave 10 times larger plate numbers. Various mobile phase mixtures (methanol, acetonitrile, water) and gradients were tested. The optimum gradient on our system is (1) 5 minutes, 47 % methanol/40 % acetonitrile/13 water in a linear gradient to (2) 17 minutes, 49 % methanol/40 % acetonitrile/11 % water to (3) 18 minutes, 29 % methanol/60 % acetonitrile/11 % water linearly to (4) 50 minutes, 31 % methanol/60 % acetonitrile/9 % water continued isocratically to 110 minutes. Oxidized hydroperoxides were detected by fluorescence using a post column reaction with diphenyl-1 pyrenylphosphine (DPPP). Both iron (III) and pyridine were tested as catalysts for this reaction.
Department of Chemistry

APA, Harvard, Vancouver, ISO, and other styles

14

Soor, Amritpal. "Group separation of complex mixtures by normal-phase high performance liquid chromatography and analysis by gas chromatography." [S.l. : s.n.], 2008. http://nbn-resolving.de/urn:nbn:de:bsz:289-vts-64791.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Witte, Dirk Theodoor. "High performance liquid chromatography for direct and indirect enantiomeric separations of chiral drugs." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 1992. http://irs.ub.rug.nl/ppn/297969609.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Sexton, Danessa Leann. "Determination of lactose by reversed-phase high performance liquid chromatography." [Johnson City, Tenn. : East Tennessee State University], 2004. http://etd-submit.etsu.edu/etd/theses/available/etd-0328104-212023/unrestricted/SextonD041504f.pdf.

Full text

Abstract:

Thesis (M.S.)--East Tennessee State University, 2004.
Title from electronic submission form. ETSU ETD database URN: etd-0328104-212023. Includes bibliographical references. Also available via Internet at the UMI web site.

APA, Harvard, Vancouver, ISO, and other styles

17

Ansong, Godfred. "Analysis of plant polyphenols by high performance liquid chromatography/mass spectrometry and protein binding." Oxford, Ohio : Miami University, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1083081905.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Patel, Hasmukh B. "Reversed-phase high-performance liquid chromatography : some basic studies and application in microbial transformation." Thesis, University of Bath, 1987. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379158.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Forage, Nazhat George. "RP-HPLC separation and kinetics of the decomposition products of tryptophan amadori compound." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59880.

Full text

Abstract:

Amadori rearrangement product (ARP) of tryptophan with glucose was synthesized according to a published procedure, and its decomposition was studied at two different concentrations and at two temperatures, 110$ sp circ$C and 140$ sp circ$C over a period of 6 hrs. A RP-HPLC system was developed to separate and quantitate the decomposition products of the ARP. The results indicated that, the ARP can decompose to form the following products, hydroxymethylfurfural (HMF), maltol, indole, $ beta$-carbolines (norharman and harman) and tryptophan. Further, using the same analytical method, the following systems were also analyzed for the presence of the above mentioned products (a) D-glucose and D-mannose with tryptophan; (b) D-glucose; and (c) tryptophan. In addition, rate constants and activation energies for the decomposition and formation reaction were calculated. Plausible mechanisms for the formation of the decomposition products are suggested.

APA, Harvard, Vancouver, ISO, and other styles

20

Klute, Robert Cragg. "Enantiomeric separations by HPLC : temperature, mobile phase, flow rate and retention mechanism studies /." This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06062008-171241/.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

張雅茗. "營實HPLC指紋圖譜研究初探." HKBU Institutional Repository, 2013. http://repository.hkbu.edu.hk/etd_ra/1364.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Eliser, Erica E. "Synthesis and Characterization of Amino-derived t-butyl-calix[4]arene Bonded Phases for HPLC." Youngstown State University / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1008341180.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Smith, Anita Mohler. "Objective judgement of cheese varieties by multivariate analysis of HPLC profiles." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26535.

Full text

Abstract:

An objective analytical method was developed to characterize the taste profiles of five cheese varieties. Nonvolatile water extracts of Cheddar, Edam, Gouda, Swiss, and Parmesan cheeses were analyzed by high performance liquid chromatography (HPLC) with a reversed phase column. The HPLC operating conditions were determined with Mapping Super-Simplex followed by Centroid Mapping Optimization. A ternary gradient elution system was used with an Adsorbosphere C8 column to resolve a maximum number of components. The optimum solvent volume ratio was 96.8 : 1.2 : 2.0 for trifluoroacetic acid (0.1%), acetonitrile, and methanol, with a flow rate of 1.0 mL/min. Over 50.3 min this ratio was changed to 56.3 : 30.3 : 13.4. Multivariate statistical analyses including principal component and discriminant analyses were applied to 55 peak areas from 106 cheese chromatograms. Principal component analysis reduced the dimensionality of the "data from 55 to 17 principal components, which are-combinations of the original variables, with a 26% loss of explained sample variation. Discriminant analysis on data from a single HPLC column was able to correctly classify cheeses by variety at a greater than 90% success rate. This grouping rate dropped to 64% when data from all four HPLC columns was combined, implicating large between column variations. A semi-trained sensory panel correctly classified cheeses by variety at a 63% rate. This objective method provides a lasting fingerprint of cheese products.
Land and Food Systems, Faculty of
Graduate

APA, Harvard, Vancouver, ISO, and other styles

24

Dotlich, Erin Michele. "ALKYLAMMONIUM FORMATE IONIC LIQUIDS AS SOLVENTS FOR FLUORESCENCE AND LIQUID CHROMATOGRAPHY METHODS." Miami University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=miami1208983119.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Huyghues-Despointes, Alexis. "Synthesis, characterization, and approaches to the analysis by HPLC-THG-AAS of trimethylselenonium, selenoniumcholine and selenoniumacetylcholine cations." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59977.

Full text

Abstract:

Selenonium cations are electron deficient species in which the central selenium atom is bonded to three carbon chains (aryl or alkyl). Trimethylselenonium iodide was synthesized by reaction of methyllithium with metallic selenium to produce methylselenolithium which was, in turn, reacted with the appropriate alkylbromide. The selenide thus formed was further methylated at the selenium atom with methyl iodide in methanol in the presence of sodium tetraphenylborate. After several recrystallizations the selenonium analytes were characterized by AAS, FT-IR, $ sp1$H-NMR, $ sp{13}$C-NMR, FAB-MS and LAMMA spectroscopic techniques and used as standards for analytical methods development.
The analysis was performed by high performance liquid chromatography with atomic absorption detection. The chromatography on a cynopropyl silica bonded phase was optimized for mobile phase composition by response surface analysis. The resulting surface response plots permitted a differentiation between the mechanisms of action of two mobile phase modifiers: triethylamine and trimethylsulfonium iodide. The improvement in chromatographic efficiency resulted in two to three fold decrease in the limit of detection. An extraction procedure with liquefied phenol was evaluated for the determination, by HPLC-AAS, of traces of selenonium cations in biological samples. The advantages and shortcomings of the HPLC-THG-AAS approach are discussed.

APA, Harvard, Vancouver, ISO, and other styles

26

Murphy, Kellyann M. "Analysis of Biodiesel Quality Using Reversed Phase High-Performance Liquid Chromatography." Scholarship @ Claremont, 2012. http://scholarship.claremont.edu/pomona_theses/45.

Full text

Abstract:

The alternative fuel biodiesel is produced from the transesterification of vegetable oils or animal fat to fatty acid methyl esters. Pomona has a reactor on campus that can be used to run this reaction and produce biodiesel. The use of biodiesel has been found to lower air pollutant and greenhouse gas emissions, but can be potentially harmful to the engines if it contains impurities. This paper proposes a method using high-performance liquid chromatography to test the quality of biodiesel. This method utilizes instrumentation and materials that are available in Pomona College's Chemistry Department, requires very little sample preparation, and is relatively safe, as long as general lab safety practices are followed. This method can also be used to optimize the procedure used to make the biodiesel. An optimized production procedure and a test method to assess the final product will ensure high quality fuel that can be used with confidence in diesel engines. This will likely add strength to proposals to increase the use of the on-campus reactor and produce biodiesel for campus grounds equipment from waste vegetable oil.

APA, Harvard, Vancouver, ISO, and other styles

27

Palmero, David A. "Comparison of cyclic voltammetry and HPLC for the determination of phenol in over-the counter sore throat sprays /." View abstract, 1999. http://library.ctstateu.edu/ccsu%5Ftheses/1540.html.

Full text

Abstract:

Thesis (M.S.)--Central Connecticut State University, 1999.
Thesis advisor: James V. Arena, Ph. D. " ... in partial fulfillment of the requirements for the degree of Master of Science in Chemistry." Includes bibliographical references (leaf 48).

APA, Harvard, Vancouver, ISO, and other styles

28

Bottegal, Megan N. "The Development of High Performance Liquid Chromatography Systems for the Analysis of Improvised Explosives." FIU Digital Commons, 2010. http://digitalcommons.fiu.edu/etd/154.

Full text

Abstract:

Existing instrumental techniques must be adaptable to the analysis of novel explosives if science is to keep up with the practices of terrorists and criminals. The focus of this work has been the development of analytical techniques for the analysis of two types of novel explosives: ascorbic acid-based propellants, and improvised mixtures of concentrated hydrogen peroxide/fuel. In recent years, the use of these explosives in improvised explosive devices (IEDs) has increased. It is therefore important to develop methods which permit the identification of the nature of the original explosive from post-blast residues. Ascorbic acid-based propellants are low explosives which employ an ascorbic acid fuel source with a nitrate/perchlorate oxidizer. A method which utilized ion chromatography with indirect photometric detection was optimized for the analysis of intact propellants. Post-burn and post-blast residues if these propellants were analyzed. It was determined that the ascorbic acid fuel and nitrate oxidizer could be detected in intact propellants, as well as in the post-burn and post-blast residues. Degradation products of the nitrate and perchlorate oxidizers were also detected. With a quadrupole time-of-flight mass spectrometer (QToFMS), exact mass measurements are possible. When an HPLC instrument is coupled to a QToFMS, the combination of retention time with accurate mass measurements, mass spectral fragmentation information, and isotopic abundance patterns allows for the unequivocal identification of a target analyte. An optimized HPLC-ESI-QToFMS method was applied to the analysis of ascorbic acid-based propellants. Exact mass measurements were collected for the fuel and oxidizer anions, and their degradation products. Ascorbic acid was detected in the intact samples and half of the propellants subjected to open burning; the intact fuel molecule was not detected in any of the post-blast residue. Two methods were optimized for the analysis of trace levels of hydrogen peroxide: HPLC with fluorescence detection (HPLC-FD), and HPLC with electrochemical detection (HPLC-ED). Both techniques were extremely selective for hydrogen peroxide. Both methods were applied to the analysis of post-blast debris from improvised mixtures of concentrated hydrogen peroxide/fuel; hydrogen peroxide was detected on variety of substrates. Hydrogen peroxide was detected in the post-blast residues of the improvised explosives TATP and HMTD.

APA, Harvard, Vancouver, ISO, and other styles

29

Wang, Tongwen. "Hyphenated HPLC-MS technique for analysis of compositional monosaccharides of transgenic corn glycoprotein and characterization of degradation products of diazinon, fonofos and aldicarb in various oxidation systems." Diss., Rolla, Mo. : University of Missouri-Rolla, 2007. http://scholarsmine.mst.edu/thesis/pdf/WangTongwen_09007dcc804e975c.pdf.

Full text

Abstract:

Thesis (Ph. D.)--University of Missouri--Rolla, 2007.
Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed April 23, 2008) Includes bibliographical references.

APA, Harvard, Vancouver, ISO, and other styles

30

Loegel, Thomas N. "High Performance Liquid Chromatography of Petroleum Asphaltenes and Capillary Electrophoresis of Glycosaminoglycan Carbohydrates." Miami University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=miami1354241855.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Lien, Wan-Fu. "Separation of Transition Metal Ions by HPLC, Using UV-VIS Detection." Thesis, North Texas State University, 1987. https://digital.library.unt.edu/ark:/67531/metadc501145/.

Full text

Abstract:

HPLC has been used and can quickly determine several ions simultaneously. The method of determination described for transition metals [Cr(III), Fe(III), Ni(II), Co(II), Cu(II), Zn(II), Cd(II), Mn(II)] and [Ca(II), Pb(II)] using HPLC with UV-VIS detection is better than the PAR complexation method commonly used. The effects of both eluent pH and detector wavelength were investigated. Results from using different pHs and wavelengths, optional analytical conditions for the separation of [Ni(II), Co(II), Cu(II)], [Cr(III), Fe(III), Ca(II), Ni(II), Cu(II)], and [Ca(II), Zn(II), Pb(II)] in one injection, respectively, are described. The influence of adding different concentrations of Na_2EDTA solvent to the sample is shown. Detection limits, linear range, and the comparisons between this study and a post-column PAR method are given.

APA, Harvard, Vancouver, ISO, and other styles

32

Suen, Kin-wah, and 孫建華. "Validation of a HPLC assay for porphobilinogen synthase in human erythrocytes for use in the clinical laboratory." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B29624897.

Full text

Abstract:

(Uncorrected OCR) Abstract Porphobilinogen (PBG) synthase condenses two molecules of aminolaevulinic acid (ALA) to form PBG in heme biosynthesis. The enzyme activity is sensitive to inhibition by heavy metals such as lead. It can act as a biological indicator of chronic lead POis~r\g to identify the risk group, especially in children, so that early treatment can be given to prevent possible permanent damages. A reversed-phase ion-pair HPLC analytical method for the assay of the PBG synthase activity based on detection of PBG production has been validated. A Hypersil CN column (150 x 4.6 mm; 5 urn) was employed together with a mixture of acetonitrile-40 mM phosphate buffer at pH 2.4 with 5 mM 1-heptanesulphonic acid (8:92, v/v). UV detection was performed at 240 nm. PBG was eluted as a spectrally pure peak resolved from its impurities in the methanol-inhibited enzyme reaction. The method was sensitive with a limit of quantitation of 2 ~M. The within-run and between-run precisions were 8.2% and 13.8% respectively. The recovery was 93.4 �7.1% (n=6). The preliminary reference range of the PBG synthase activities in the local pediatric population were from 21.5 to 26.3 ~mol/L RBC/min. Bland and Altman statistical analysis showed that the HPLC assay and the colorimetric assay could not be used interchangeably. The HPLC assay was an alternative way to assess the PBG synthase activities in the human erythrocyte samples. IV
abstract
toc
Medical Sciences
Master
Master of Medical Sciences

APA, Harvard, Vancouver, ISO, and other styles

33

Hanan, Nathan, and David Nix. "Extending the Stability of Intravenous Ampicillin." The University of Arizona, 2012. http://hdl.handle.net/10150/614496.

Full text

Abstract:

Class of 2012 Abstract
Specific Aims: To assess the chemical stability of ampicillin for injection in normal saline at pH values ranging from 5 to 6. Methods: A stability-indicating high performance liquid chromatography (HPLC) method was developed and used to determine the stability of ampicillin for injection in normal saline following buffering with sodium acetate and acid adjustment with HCl at pH values of 5, 5.5, and 6. To confirm that the assay was stability-indicating, ampicillin trihydrate reference standard (1 mg/mL) was exposed to alkali, acid, and oxidative stress conditions and analyzed by HPLC for the presence of degradation products. Analysis was performed on a reverse-phase (C-18) column with a mobile phase consisting of water, acetonitrile, 1 M monobasic potassium phosphate, and 1 N acetic acid (909:80:10:1). Other HPLC parameters were: flow rate 1 mL/min; detection wavelength 254 nm; injection volume 20 µL; column temperature 30˚C. The method was evaluated for linearity, precision, and accuracy. The chemical stability of ampicillin for injection (18 mg/mL) in normal saline and sodium acetate (pH adjusted at values of 5, 5.5, and 6) was assessed at baseline (t=0), 7, 11, 17, 31, and 44 hours and compared to a control solution (no pH adjustment). Measurements at each time interval were performed in triplicate. Main Results: Ampicillin trihydrate reference standard (1 mg/mL) was adequately separated from degradation products following exposure to alkali, acid, and oxidative stress conditions. After 16 hours, a precipitate was observed in the solution at pH 6, and therefore stability is not reported. All other solutions (pH 5, pH 5.5, and control) were stable for at least 24 hours at room temperature and yielded t90 values of 110, 64.2, and 27.5 hours, respectively. Conclusions: Adjustment of intravenous ampicillin solutions to pH values of 5 or 5.5 significantly increased stability. Ampicillin appears to be most stable at a pH near its isoelectric point (pH 5).

APA, Harvard, Vancouver, ISO, and other styles

34

Li, Cheuk Fai. "Studies of flow injection system for micelle-assisted preconcentration of PAHs coupled with HPLC." HKBU Institutional Repository, 2009. http://repository.hkbu.edu.hk/etd_ra/1059.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Marques, Tamires Valim 1987. "Desenvolvimento e validação de método analítico empregando DLLME e HPLC/UV para determinação de benzodiazepínicos em amostra de água." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265966.

Full text

Abstract:

Orientador: Rodnei Bertazzoli
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
Made available in DSpace on 2018-08-24T13:08:38Z (GMT). No. of bitstreams: 1 Marques_TamiresValim_M.pdf: 6834346 bytes, checksum: 5eb1bc6d88a438ca9002c92109a6c660 (MD5) Previous issue date: 2014
Resumo: A crescente preocupação com a poluição das águas por novos poluentes denominados emergentes tem se intensificado, visto que aumentou o número destes compostos detectados em água. Dentre estes compostos encontram-se os fármacos e produtos de higiene pessoal, usados cotidianamente pela população. O presente trabalho teve como objetivo o desenvolvimento de um método simples, rápido e sensível utilizando a microextração líquido líquido (DLLME) combinada com a cromatografia líquida de ultra eficiência (HPLC) com detecção ultravioleta (UV) para a determinação de alguns benzodiazepínicos (bromazepam, clonazepam e diazepam) em amostras de água. A determinação foi realizada em uma coluna C18 de acordo com as condições cromatográficas ótimas (fase móvel acetonitrila:água (60:40, v/v); vazão 1,2 mL min-1; detecção 225 nm). No método de extração, uma mistura apropriada de solvente extrator e dispersor foi injetada rapidamente na amostra aquosa (10 mL) com auxílio de uma seringa. De modo que uma solução turva foi formada, esta solução é caracterizada por conter pequenas partículas do solvente extrator que se dispersa na fase aquosa. Os parâmetros da extração, tais como natureza e volume dos solventes extrator e dispersor, tempo de extração, pH da amostra, força iônica, velocidade e tempo de centrifugação, foram estudados para a otimização. Com as condições ótimas definidas (solvente extrator: clorofórmio, 200 ?L; solvente dispersor: metanol, 700 ?L; pH da amostra 9,0; velocidade e tempo de extração: 5000 rpm, 1 minuto; força iônica: adição de 1% (p/v) de (NH4)2SO4) o método proposto foi validado seguindo as figuras de método preconizadas pela ANVISA na Resolução N° 899 de 2003. A faixa linear para cada fármaco foram 8,0 - 96 ?g L-1 para bromazepam, 4,0 - 48 ?g L-1 para clonazepam e 1,0 - 12 ?g L-1 para diazepam. Todas as curvas obtiveram valores de (r) superiores a 0,999. Os limites de detecção e quantificação obtidos foram 2,4 e 8,0 ?g L-1 para bromazepam, 1,2 e 4,0 ?g L-1 para clonazepam, 0,2 e 1,0 ?g L-1 para diazepam, respectivamente. As recuperações variaram de 50 a 110% com RSD (Desvio Padrão Relativo) inferiores a 12,7 %. Finalmente, o método proposto foi aplicado em amostras coletadas na represa Billings localizada no município de Diadema-SP.
Abstract: The growing concern over water pollution caused by so-called new emerging pollutants has intensified since increased the number of these compounds detected in water. Among these compounds are pharmaceuticals and personal care products used daily by the population. This study aimed to develop a simple, rapid and sensitive liquid using liquid micro extraction (DLLME) combined with ultra-performance liquid chromatography (HPLC ) with ultraviolet detection (UV) for the determination of some benzodiazepines (bromazepam, clonazepam and diazepam) in water samples . The determination was performed on a C18 column in accordance with the optimal chromatographic conditions (mobile phase acetonitrile: water (60:40, v/v), flow rate 1.2 mL min-1, detection 225 nm). In the extraction method, a suitable mixture of extractant and dispersing solvent was injected rapidly into the aqueous sample (10 ml) with a syringe. So that a cloudy solution was formed, this solution is characterized by containing fine drops of the extractor solvent is dispersed in the aqueous phase. The parameters of the extraction, such as the nature and volume of the extractor and disperser solvents, extraction time, sample pH, ionic strength, speed and time of centrifugation, were studied for optimization. With the defined optimal conditions (extracting solvent: chloroform, 200 ?L; disperser solvent: methanol, 700 ?L, sample pH 9.0, extraction time and speed: 5000 rpm, 1 minute; ionic strength: adding 1% (p/v) (NH4)2SO4) the proposed method was validated following the figures of merit recommended by the ANVISA Resolution No. 899 of 2003. The linear ranges for each drug were 8.0 to 96 ?g L- 1 for bromazepam, 4.0 to 48 ?g L- 1 for clonazepam and 1.0 to 12 ?g L- 1 for diazepam. All curves obtained values (r) greater than 0.999. The limits of detection and quantification obtained were 2.4 and 8.0 ?g L- 1 to bromazepam, 1.2 and 4.0 ?g L- 1 to clonazepam, 0.2 and 1.0 ?g L- 1 for diazepam, respectively. Recoveries ranged from 50 to 110% with RSD (Relative Standard Deviation) of less than 12.7%. Finally, the proposed method was applied to samples collected in the Billings dam located in Diadema-SP.
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica

APA, Harvard, Vancouver, ISO, and other styles

36

Wang, Yu. "HPLC method development for the evaluation of pheromones from the dwarf African clawed frog Hymenochirus." Scholarly Commons, 2003. https://scholarlycommons.pacific.edu/uop_etds/587.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Hayteas, David Lawrence. "HPLC analysis of myoglobin tryptic peptides from selected species of cetaceans." PDXScholar, 1990. https://pdxscholar.library.pdx.edu/open_access_etds/4086.

Full text

Abstract:

Due to the large gaps in the fossil record, the evolutionary history of the mammalian order Cetacea is incomplete and controversial. Increasingly researchers are utilizing molecular and biochemical procedures to supplement cetacean paleontology. One of these methods is the comparison of amino acid sequences of myoglobin among species of this order. since this method is time-consuming and expensive, an alternative procedure is desirable.

APA, Harvard, Vancouver, ISO, and other styles

38

Van, Meter David S. III. "Synthesis and Characterization of Surface-Confined Ionic Liquid Stationary Phases for High Performance Liquid Chromatography." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1227275073.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Perdue, James D. "The removal of Cremophor® EL from paclitaxel for quantitative analysis by HPLC-UV /." Electronic version (PDF), 2005. http://dl.uncw.edu/etd/2005/perduej/jamesperdue.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Collins, Matthew P. "Reversed Phase Liquid Chromatography Using the Ionic Liquid Isopropylammonium Formate and Comparison of Indirect Spectrophotometric Methods for Phosphate." Miami University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=miami1312342055.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Almassalkhi, Brittany A. "Arsenic Speciation, Detection, and Quantification in Drinking Water using High Performance Liquid Chromatography and Inductively Coupled Plasma Mass Spectrometry." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1258580087.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Brannegan, Daniel Robert. "Analysis of Ethoxyquin and its Oxidation Products using Supercritical Fluid Extraction and High Performance Liquid Chromatography with Chemiluminescent Nitrogen Detection." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/31575.

Full text

Abstract:

Ethoxyquin is an antioxidant commonly used to preserve vitamins and lipids in various food products and animal feeds. The extraction and determination of ethoxyquin is becoming increasingly important as products, which are labeled as "natural" are becoming more common. The present method of determination only ensures that ethoxyquin values are below 10-20 parts per million. Therefore, advances are needed in methods of extraction and analysis in order to lower the detection limits in various products. The first part of this research investigates the use of supercritical fluids in the extraction of ethoxyquin from lean beef and beef fat. Supercritical fluids offer the advantages of safety, time, expense, and selectivity over liquid extractions. Three fluids were examined: carbon dioxide, trifluoromethane, and 1,1,1,2-tetrafluoroethane. Carbon dioxide appeared to react with ethoxyquin during the extraction. Methanol modified hydrofluorocarbons provided more complete extractions over pure hydrofluorocarbon fluids. Methanol modified 1,1,1,2-tetrafluoroethane was used in the extraction of ethoxyquin from lean beef and beef fat, and provided a quantitative extraction at the 0.5 ppm level. The second part of this research centered on the separation and quantitation of the oxidation products of ethoxyquin through the use of high pressure liquid chromatography with chemiluminescence nitrogen detection (HPLC/CLND). When ethoxyquin is oxidized, the resulting products also exhibit antioxidative properties. While these oxidation products are known, no effort has been made to separate and quantify them in real or clean samples. HPLC/CLND allows all nitrogen containing compounds to be quantified without a known standard. This method is of extreme interest in the case of ethoxyquin oxidation products, or other types of metabolites, where standards are difficult to obtain or are unstable. HPLC/CLND allowed a separation of ethoxyquin and four of its oxidation products to be detected, thus making future studies of the antioxidant behavior of ethoxyquin feasible.
Master of Science

APA, Harvard, Vancouver, ISO, and other styles

43

Kamble, Ujjwala Kerba. "Use of liquid chromatography for assay of flavonoids as key constituents and antibiotics as trace elements in propolis : investigation into the application of a range of liquid chromatography techniques for the analysis of flavonoids and antibiotics in propolis, and extraction studies of flavonoids in propolis." Thesis, University of Bradford, 2016. http://hdl.handle.net/10454/14564.

Full text

Abstract:

Propolis is an approved food additive containing flavonoids as a major active constituent. Variability has been found in the composition of propolis in distinctive regions and it was noticed that there are limitations in the analysis of propolis. In this study, the identification of ten flavonoids and residual antibiotics in propolis was investigated by using several liquid chromatography techniques, including reversed-phase high-performance liquid chromatography (RP-HPLC), microemulsion LC (MELC) and ultra-performance LC (UPLC). The ten flavonoids that were selected for this research include rutin, myricetin, quercetin, apigenin, kaempferol, pinocembrin, CAPE, chrysin, galangin and acacetin while chlortetracycline, oxytetracycline and doxycycline were selected to examine the residual antibiotics in propolis. For the analysis of the selected flavonoids, routine RP-HPLC method was found to be the best method, while MELC technique was found more efficient for the analysis of the selected antibiotics. Solid phase extraction with HLB sorbent was utilised in the analysis of antibiotics for clean-up of propolis. In method development studies for flavonoids and antibiotics, one-factor-at-a-time (OFAT) approach was followed. The final optimised method for the analysis of flavonoids as well as the method. for the analysis of antibiotics was validated using the ICH guidelines, and various aspects, such as the linearity, selectivity, accuracy, recovery, robustness and stability parameters, were examined. Development of efficient conventional method for the extraction of flavonoids from propolis was studied extensively in the present research work using different extraction techniques such as maceration, hot extraction, ultrasound assisted extraction. Among all extraction experiments, ethanolic extraction using ultrasound extraction method was the best efficient approach. This thesis shows that, in general, the performance of O/W MELC is superior to that of conventional HPLC for the determination of residual antibiotics in propolis. UPLC was not suitable for the analysis of flavonoids and antibiotics. The conventional LC was the only technique to separate the ten flavonoids but MELC was able to separate nine of the flavonoids with faster analysis time. This work also showed that MELC uses cheaper solvents. This considerable saving in both cost and time will potentially improve efficiency within quality control.

APA, Harvard, Vancouver, ISO, and other styles

44

Nascimento, DemÃtrius Fernandes do. "Nimodipine determination in human plasma by high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS-MS)." Universidade Federal do CearÃ, 2005. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=31.

Full text

Abstract:

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
A rapid, specific and highly sensitive liquid chromatography-tandem mass spectrometry method was developed to determine nimodipine in human plasma using dibucaine as the internal standard (IS) is described. The analyte (m/z 418,6 > 342,6) and IS (m/z 344,2 > 271,0) were extracted from plasma samples by liquid-liquid extraction using hexane-ethyl acetate (1:1v/v). Chromatography was performed on a VarianÂ Polaris C18 analytical column (3 micrometer, 50 x 2,0 mm) and pre-column SecurityguardTM C18 (4,0 x 3,0 mm). The phase mobile consisted of Acetonitrile-Ammonium acetate 0.02 ml/L (80:20v/v). The method had a chromatographic run time of 4.5 min and linear calibration curve over the range 0.1- 40 ng/mL (r2 > 0.9938). The limit of quantification (LQ) was 0.1 ng/mL. The intra-day precision for the limit quantification was 0.00% (batch 01), 5.71% (batch 02) and 5.27% (batch 03); for the quality controls low (QCL), middle (QCM) and high (QCH) the results were respectively 8.57, 0.81 and 1.37%. The inter-day precision for LQ and QCL, QCM and QCH were respectively: 7% and 5.46, 4.12 and 3.37%. The intra-day accuracy for LQ was 110, 96 and 104%; for QCL, QCM and QCH the results were100.67, 109.09 and 109.72% respectively. The results of the inter-day accuracy for LQ, QCL, QCM and QCH were respectively and 110.0, 96.0, 104.0% for the limit of quantification and 8.57, 0.81, 1.37% and 100.67, 109.09, 109.72% respectively: 103% e 102.89, 106.60, 109.69%. This validated method was successfully applied for the pharmacokinetic profiles of nimodipine tablets administered to 24 healthy volunteerâs participant of bioavailability comparative study. Geometric mean of Test formulation/Refernce formulation individual percent ratio was 104,56% for AUC0-48h and 55,73% for Cmax. The 90% for the confidence intervals (CI) were 94,80-115,32% e 44,73-69,42%, respectively. The values of half-life and Cmax for test formulation and reference formulation were 27,83;32,78h and 9,48;18,76ng/mL, respectively. The values of Tmax were 2,34;0,98h for the formulations test and reference respectively. Since the 90% CI for Cmax and AUC0-48h, were within the 80-125% interval proposed by the âFood and Drug Administrationâ and ANVISA, it was concluded that the two formulations of nimodipine 30mg tablets were not bioequivalent, according to the rate of absorption after single dose administration.
Um mÃtodo rÃpido, sensÃvel e especÃfico de Cromatografia LÃquida de Alta EficiÃncia acoplada Ã Espectrometria de Massa (LC-MS-MS) foi desenvolvido para determinar nimodipino (analito) em plasma humano usando dibucaÃna como padrÃo interno (PI). O analito (m/z 418,6 > 342,6) e o PI (m/z 344,2 > 271,0) foram extraÃdos de amostras de plasma atravÃs de extraÃÃo lÃquido-lÃquido utilizando hexano-acetato de etila (1:1v/v). As corridas cromatogrÃficas foram executadas utilizando-se uma coluna analÃtica VarianÂ Polaris C18 (3 micrÃmetros, 50 x 2,0 mm) e uma prÃ-coluna SecurityguardTM C18 (4,0 x 3,0 mm). A fase mÃvel consistiu de acetonitrila-soluÃÃo de acetato de amÃnio 0,02 mol/L (80:20v/v). O mÃtodo teve um tempo total de corrida de 4,5 min e uma curva de calibraÃÃo linear que variou de 0,1-40 ng/mL. O limite de quantificaÃÃo de 0,1 ng/mL. A precisÃo intra-ensaio para o limite de quantificaÃÃo (LQ) foi 0,00% (lote 01), 5,71% (lote 02) e 5,27% (lote 03); para os controles de qualidade baixo (CQB), mÃdio (CQM) e alto (CQA) os resultados foram respectivamente: 8,57, 0,81 e 1,37%. A precisÃo interensaio para o LQ e os CQB, CQM e CQA foram respectivamente de: 7% e 5,46, 4,12 e 3,37%. A exatidÃo intra-ensaio para o LQ foi 110, 96 e 104%; para CQB, CQM e CQA os resultados foram 100,67, 109,09 e 109,72% respectivamente. Os resultados da exatidÃo interensaio para o LQ, CQB, CQM e CQA foram respectivamente de: 103% e 102,89, 106,6, 109,69%. Este mÃtodo foi aplicado para a avaliaÃÃo do perfil farmacocinÃtico do nimodipino administrado em 24 voluntÃrios sadios participantes de um estudo de biodisponibilidade comparativa. A mÃdia geomÃtrica da FormulaÃÃo teste/FormulaÃÃo referÃncia para as porcentagens individuais foi 104,56% para ASC0-48h e 55,73% para Cmax. Os intervalos obtidos a partir do intervalo de confianÃa (IC) de 90% foram 94,80-115,32% e 44,73-69,42% respectivamente. Os valores de meia-vida e Cmax para as formulaÃÃes teste e referÃncia foram de 27,83;32,78h e 9,48;18,76ng/mL, respectivamente. Os valores de Tmax foram de 2,34;0,98h para as formulaÃÃes teste e referÃncia, respectivamente. Considerando o IC de 90% para Cmax e ASC0-48h dentro da variaÃÃo de 80-125% proposto pelo Food and Drug Administration e ANVISA, as duas formulaÃÃes de nimodipino 30mg nÃo sÃo bioequivalentes quanto Ã taxa de absorÃÃo (Cmax) apÃs uma Ãnica administraÃÃo.

APA, Harvard, Vancouver, ISO, and other styles

45

Rösemann, G. M. "Analysis of pyrrolizidine alkaloids in Crotalaria species by HPLC-MS/MS in order to evaluate related food health risks." Electronic thesis, 2006. http://upetd.up.ac.za/thesis/available/etd-08032007-170633/.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Pane, Daniela de Queiroz 1977. "Desenvolvimento, validação e aplicação de metodologia para determinação de edulcorantes por HPLC." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/254271.

Full text

Abstract:

Orientador: Helena Teixeira Godoy
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-08-19T15:35:59Z (GMT). No. of bitstreams: 1 Pane_DanieladeQueiroz_D.pdf: 2989651 bytes, checksum: 1f92009c2aa35df54d0c45737049c170 (MD5) Previous issue date: 2012
Resumo: Foi desenvolvido um novo método, eficiente e econômico, para a análise simultânea de cinco edulcorantes em alimentos (acessulfame-k, sacarina, ciclamato, aspartame e neotame) pela técnica de cromatografia líquida de alta eficiência (HPLC). O método foi validado e aplicado em diferentes produtos da categoria "light¿, "diet¿ e "zero¿, sendo esses refrigerantes, néctares, pós para preparo de refresco, pudins, cappuccinos, achocolatados, geléias, gelatina, molho tipo "barbecue¿, catchup e adoçantes de mesa. Para tanto, utilizou-se uma coluna C18, fase móvel composta por fase aquosa (5 mM de tampão fosfato de sódio monobásico; pH 7) e fase orgânica (acetonitrila), eluição por gradiente, vazão de 0,4 mL.min-1 e temperatura de 56ºC. Os edulcorante apresentaram adequada linearidade na faixa de trabalho. A repetitividade, a precisão intermediária e os limites de detecção e de quantificação foram adequados para os cinco edulcorantes. As taxas de recuperação variaram entre 85,2% e 101,4%, para as diferentes matrizes avaliadas. O método apresentou uma limitação para as amostras contendo cacau, onde não foi possível determinar o ciclamato em virtude da presença de um interferente. Até três edulcorantes utilizados em combinação foram encontrados nas amostras, sendo acessulfame-k e aspartame os mais comumente empregados. As amostras de pudim sabor chocolate, molho tipo "catchup¿ e molho tipo "barbecue¿ apresentaram concentrações de edulcorantes acima do permitido pela legislação brasileira. As amostras de refrigerante sabor limão, sabor guaraná, tipo cola e de refresco em pó, embora estivessem atendendo a legislação, apresentaram teor de edulcorantes acima do declarado no rótulo. O método desenvolvido por HPLC foi comparado a uma metodologia por cromatografia líquida de ultra eficiência (UPLC) e apresentou maior robustez e menor custo em comparação ao desenvolvimento para UPLC. Já o método por UPLC demonstrou baixo consumo de solventes, tempo curto de análise, menores limites de detecção e de quantificação, no entanto, maior custo devido ao preparo das amostras e à coluna, solventes, reagentes e filtros envolvidos nas análises
Abstract: We developed a new method, efficient and economical, for the simultaneous analysis of five sweeteners in foods (acesulfame K, saccharin, cyclamate, aspartame and neotame) technique for high performance liquid chromatography (HPLC). The method was validated and applied to different products in the "light", "diet" and "zero", and these soft drinks, nectars, powders for preparation of soft drinks, puddings, cappuccino, chocolate, jams, jelly, sauce type "barbecue" , ketchup and tabletop sweeteners. To both, we used a C18 column, mobile phase consisting of aqueous phase (5 mM sodium phosphate buffer monobasic; pH 7) and organic phase (acetonitrile), gradient elution, flow of 0.4 mL.min-1 and temperature of 56 º C. The sweetener showed acceptable linearity in the range of work. The repeatability, intermediate precision and limits of detection and quantification were adequate for the five sweeteners. Recovery rates ranged between 85.2% and 101.4% for the different matrices evaluated. The method has a limitation for samples containing cocoa, which was not possible to determine cyclamate because of the presence of an interferer. Up to three sweeteners used in combination were found in the samples, with aspartame and acesulfame-k the most commonly employed.Samples of chocolate pudding flavored sauce like "ketchup" sauce like "barbecue" sweeteners showed concentrations above those permitted by Brazilian law. Samples of lemon-flavored soda, flavored guarana, cola and powdered drink mixes, although they were given the rules presented above sweeteners content declared on the label. The method developed HPLC method was compared to an ultra performance liquid chromatographic efficiency (UPLC) and showed greater robustness and lower cost compared to developing for UPLC. Have the method by UPLC demonstrated low consumption of solvents, short time of analysis, lower limits of detection and quantification, however, higher cost due to preparation of samples and the column, solvents, reagents and filters involved in the analyzes
Doutorado
Ciência de Alimentos
Doutor em Ciência de Alimentos

APA, Harvard, Vancouver, ISO, and other styles

47

Nestola, Marco [Verfasser], and Torsten Claus [Akademischer Betreuer] Schmidt. "Multidimensional high-performance liquid chromatography–gas chromatography (HPLC-GC) hyphenation techniques for food analysis in routine environments / Marco Nestola ; Betreuer: Torsten Claus Schmidt." Duisburg, 2016. http://d-nb.info/1115654659/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Shao, Peimin. "SFE Fractionation and RP-HPLC Characterization of Aquatic Fulvic Acid." Thesis, University of North Texas, 1994. https://digital.library.unt.edu/ark:/67531/metadc500352/.

Full text

Abstract:

The Supercritical Fluid Extraction (SFE) technique was used to fractionate Suwannee River reference fulvic acid (FA). The fractions were characterized by gas chromatography (GC) and reversed-phase high performance liquid chromatography (RP-HPLC). A SFE fractionation method was developed using stepwise gradient of supercritical CO₂ and methanol. Three FA fractions were separated. The average mass recovery was 102% with the coefficient of variation of 2.8%. The fractionation dynamics and the difference in the ratios of UV absorption to fluorescence emission indicate the real fractionation of the FA. The HPLC chromatographic peak patterns and the spectra of the corresponding peaks were almost indistinguishable. The overall results of this research support the argument that FA exhibits polymer-like molecular structure.

APA, Harvard, Vancouver, ISO, and other styles

49

Forssén, Patrik. "Adsorption Isotherm Parameter Estimation in Nonlinear Liquid Chromatography." Doctoral thesis, Uppsala universitet, Avdelningen för teknisk databehandling, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5971.

Full text

Abstract:

This thesis concerns the development and validation of methods for the industrially important area of adsorption isotherm parameter estimation in preparative, nonlinear high performance liquid chromatography (HPLC). Preparative chromatography is a powerful separation method to get pure compounds from more or less complex liquid mixtures, e.g., mixtures of mirror-image molecules. Computer simulations can be used to optimize preparative chromatography, but then competitive adsorption isotherm parameters are usually required. Here two methods to estimate adsorption isotherm parameters are treated: (i) the perturbation peak (PP) method and (ii) the inverse method (IM). A new theory for the PP method was derived and led to a new injection technique which was validated experimentally. This injection technique solved the severe problem with vanishing peaks and enabled us to use the PP method to estimate binary competitive adsorption isotherms valid over a broad concentration range. Also, the injection technique made it possible to estimate competitive adsorption isotherms for a quaternary mixture for the first time. Finally, an interesting perturbation peak phenomenon, known as the “Helfferich Paradox”, was experimentally verified for the first time. The IM is a relatively new method to determine adsorption isotherm parameters. It has the advantage of requiring very small samples, but also requires an advanced computer algorithm. An improved implementation of this computer algorithm was developed and tested experimentally. Also, a variant of the IM called “the inverse method on plateaus” was tested experimentally and the estimated adsorption isotherm parameters were shown to be valid over a broader concentration range than those estimated with the standard IM.

APA, Harvard, Vancouver, ISO, and other styles

50

Hu, Feifei. "Application of High Performance Liquid Chromatography (HPLC) and Fourier Transform Infrared (FTIR) Spectroscopy to Swiss-type Cheese Split Defects." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1343392495.

Full text

APA, Harvard, Vancouver, ISO, and other styles

We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!