Title page for ETD etd-11252009-235345

Document Type Master's Dissertation
Author Marais, Adriaan Albertyn Scheepers
URN etd-11252009-235345
Document Title Applications of extractive-derivatization sample preparation in a clinical toxicology laboratory setting
Degree MSc
Department Chemical Pathology
Advisor Name Title
Dr J B Lourens Supervisor
  • biosamples
  • gas chromatography-mass spectrometry
  • toxicology
Date 2009-09-05
Availability unrestricted
The metabolism of absorbed xenobiotic compounds in humans results in a mixture of target compounds applicable for analysis, trapped in complex biological matrices. Gas chromatography-mass spectrometry (GC-MS) is a powerful analytical technique that has been successfully applied in the analysis of volatile and semi-volatile compounds from complex biological samples. This is due to the ability of GC-MS to separate different sample constituents at trace levels while providing accurate molecular structural information for the resolved compounds. The complexity of biological specimens and their largely aqueous nature, combined with the physicochemical properties of target analytes resulting from metabolism, greatly precludes direct analysis of biosamples by GC-MS. Traditionally, highly laborious and time consuming sample preparation procedures are performed to isolate and chemically alter target analytes to attain suitable amenity for the detection system. Furthermore, routine analytical procedures in clinical toxicology laboratories are signified by short specimen turn-around times. The commonplace use of GC-MS in modern-day laboratories still suffer from prolonged turn-around times that result from both sample preparation steps and lengthy instrumental analysis. Simplified and cost-effective analytical procedures capable of extracting multiple analytes, with divergent functional groups, from biological matrices in a timely manner are therefore required.

To address this issue, this work describes the development of validated extractive-derivatization methods combined with fast GC-MS analysis for expedient and accurate quantitation of different analytes in occupational monitoring and workplace drug testing. Extractive alkylation of acidic analytes phenol, o-cresol, mandelic acid, hippuric acid, and (o-, m-, p-) methylhippuric acid for simultaneous urinary bio-monitoring of occupational exposure to benzene, toluene, ethylbenzene, and xylene, respectively, is performed. Extractive acylation for simultaneous urinary confirmation of basic analytes amphetamine, methamphetamine, norephedrine, methcathinone, ephedrine, methylenedioxyamphetamine (MDA), methylenedioxymethamphetamine (MDMA), methylenedioxyethylamphetamine (MDEA) and N-methyl-1-(3,4 methylenedioxyphenyl)-2-butanamine (MBDB) in workplace drug testing is performed. The successful combination of abovementioned techniques alongside fast GC-MS allows increased sample throughput and decreased turn-around time for routine analysis while maintaining bioanalytical quantitative criteria, as required in a clinical toxicology laboratory setting.

2009, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.

Please cite as follows:

Marais, AAS 2009, Applications of extractive-derivatization sample preparation in a clinical toxicology laboratory setting, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-11252009-235345/ >


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