Masters Theses

Abstract

"Alpha hydroxy acids (AHAs) - carboxylic acids with a hydroxyl substitution on the alpha carbon are an important class of molecules. Hydroxy Methyl Thiobutanoic Acid (HMTBA) is an α-hydroxy analog of essential amino acid methionine; it finds extensive use as a feed supplement for avian and bovine species. Efficacy of alpha hydroxy acid uptake is important for nutritional studies and such studies rely on accurate and precise methods for determination of these chemicals in biological samples. Several methods for AHAs determination have been reported, however, the methods are tedious, requiring multiple sample preparation steps. Experiments reported in this thesis were aimed at development of a method that is simple, accurate and precise. The method involved lyophilization of sample matrices (bovine blood serum or seawater), extraction of the residues with solvents such as acetone or methanol, and reconstitution of the extracts in a suitable solvent system. The solvent system was dependent on the instrumental method used for final determination. The reconstituted extracts were then analyzed with liquid or the gas chromatography interfaced to mass spectrometry (HPLC-MS, GC-MS) or directly with electrospray ionization mass spectrometry (ESI-MS). Validation experiments with fortified synthetic seawater and bovine blood serum samples showed that analyte recoveries were consistently in the 90-100% range and analytes were readily monitored over a 0.01 - 50 parts per million concentration range. Improved selectivity was achieved through S - methylation of HMBTA to the sulfonium chloride cation. The cation was readily detected through direct introduction into ESI-(MS)² and monitoring for a fragment ion at m/z 103 resulting from molecular ion m/z 165 with the loss of dimethyl sulfide as the neutral species"--Abstract, page iii.

Advisor(s)

Kapila, Shubhender

Committee Member(s)

Nam, Paul Ki-souk
Flanigan, V. J.

Department(s)

Chemistry

Degree Name

M.S. in Chemistry

Publisher

Missouri University of Science and Technology

Publication Date

2008

Pagination

ix, 55 pages

Note about bibliography

Includes bibliographical references.

Rights

© 2008 Ryan Schwiderski, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Subject Headings

Hydroxy acidsTrace analysis -- MethodologyMass spectrometryChromatographic analysisGas chromatographyLiquid chromatography

Thesis Number

T 10216

Print OCLC #

862120026

Electronic OCLC #

862120281

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