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Stir bar sorptive extraction and gas chromatography : mass spectrometry for the analysis of biological matrices
Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2007.
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| Other Authors: | |
| Format: | Thesis |
| Language: | English |
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Stellenbosch : University of Stellenbosch
2008
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| _version_ | 1867613964386435072 |
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| access_status_str | Open Access |
| author | Stopforth, A. |
| author2 | Sandra, P. J. F. |
| author_browse | Sandra, P. J. F. Stopforth, A. |
| author_facet | Sandra, P. J. F. Stopforth, A. |
| author_sort | Stopforth, A. |
| collection | Thesis |
| dc_rights_str_mv | University of Stellenbosch |
| description | Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2007. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/1143 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:44:30.757Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2008 |
| publishDateRange | 2008 |
| publishDateSort | 2008 |
| publisher | Stellenbosch : University of Stellenbosch |
| publisherStr | Stellenbosch : University of Stellenbosch |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/1143 Stir bar sorptive extraction and gas chromatography : mass spectrometry for the analysis of biological matrices Stopforth, A. Sandra, P. J. F. Crouch, A. M. Burger, B. V. University of Stellenbosch. Faculty of Science. Dept. of Chemistry and Polymer Science. Dissertations -- Chemistry Theses -- Chemistry Gas chromatography Mass spectrometry Extraction (Chemistry) Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2007. This study describes the development of simplified analytical methods for the analysis of trace quantities of selected naturally occurring target compounds in complex biological matrices by stir bar sorptive extraction (SBSE) and gas chromatography/mass spectrometry (GC/MS). SBSE facilitates the direct extraction of organic compounds from aqueous samples by allowing the solutes to partition between the aqueous phase and a glass stir bar that is coated with a layer of polydimethylsiloxane (PDMS). The partitioning of polar compounds into the PDMS coating was enhanced by using different derivatization techniques in combination with SBSE. The derivatization of polar functional groups was performed with ethyl chloroformate, acetic acid anhydride, and O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine directly in the aqueous samples. Headspace derivatization of compounds containing a secondary alcohol group was performed directly on the stir bar coating in the presence of acetic acid anhydride vapors. The derivatized compounds were thermally desorbed (TD) and analyzed on-line by GC/MS. A number of experimental parameters, including salt addition, temperature and time were optimized to improve the recovery of the derivatized compounds by SBSE. The optimized methods were validated in terms of linearity, precision, and detection and quantitation limits prior to performing the quantification. Trace levels of tuberculostearic acid, a marker of tuberculosis, was detected in sputum samples that were decontaminated and concentrated before being analyzed by SBSE-TD-GC/MS. The method is sufficiently sensitive to detect the marker without the need to culture the organisms, namely M. Tuberculosis. The analysis of 4-hydroxynonenal has also been demonstrated by detecting trace levels of this oxidative stress marker in urine samples obtained from healthy volunteers. Furthermore, abnormally low testosterone/epitestosterone ratios were detected in a group of HIV positive patients by means of SBSE-TD-GC/MS. Further research is required to determine the clinical significance of this finding in the context of HIV infection. Finally, the excessive urinary excretion of estrone and 17β-estradiol following the administration of a high dose of the conjugated equine estrogens to a female volunteer has also been demonstrated. Doctoral 2008-04-14T09:55:35Z 2010-06-01T08:13:34Z 2008-04-14T09:55:35Z 2010-06-01T08:13:34Z 2007-12 Thesis http://hdl.handle.net/10019.1/1143 en University of Stellenbosch 2550740 bytes application/pdf application/pdf Stellenbosch : University of Stellenbosch |
| spellingShingle | Dissertations -- Chemistry Theses -- Chemistry Gas chromatography Mass spectrometry Extraction (Chemistry) Stopforth, A. Stir bar sorptive extraction and gas chromatography : mass spectrometry for the analysis of biological matrices |
| title | Stir bar sorptive extraction and gas chromatography : mass spectrometry for the analysis of biological matrices |
| title_full | Stir bar sorptive extraction and gas chromatography : mass spectrometry for the analysis of biological matrices |
| title_fullStr | Stir bar sorptive extraction and gas chromatography : mass spectrometry for the analysis of biological matrices |
| title_full_unstemmed | Stir bar sorptive extraction and gas chromatography : mass spectrometry for the analysis of biological matrices |
| title_short | Stir bar sorptive extraction and gas chromatography : mass spectrometry for the analysis of biological matrices |
| title_sort | stir bar sorptive extraction and gas chromatography mass spectrometry for the analysis of biological matrices |
| topic | Dissertations -- Chemistry Theses -- Chemistry Gas chromatography Mass spectrometry Extraction (Chemistry) |
| url | http://hdl.handle.net/10019.1/1143 |
| work_keys_str_mv | AT stopfortha stirbarsorptiveextractionandgaschromatographymassspectrometryfortheanalysisofbiologicalmatrices |