Date of Award

1-1-2012

Document Type

Campus Access Dissertation

Department

Chemistry and Biochemistry

Sub-Department

Chemistry

First Advisor

Stephen L Morgan

Abstract

This dissertation focuses on the chemical analyses of N-nitrosonornicotine from (NNN) porcine esophageal tissue, benzodiazepines (BZDs) and steroids in urine, and toxins such as melamine and pesticides in various foods. The effects of menthol, ethanol and also acetaldehyde on the flux of NNN permeation across porcine esophageal tissue were studied using Franze diffusion cells. Using LC/MS/MS, the limit of detection (LOD) and limit of quantification (LOQ) of NNN levels were 0.065 and 0.196 ppb, respectively. Alcohol (20 and30%) and the presence of menthol and acetaldehyde (10, 20, and 30%) significantly increased permeation of NNN through porcine esophageal tissue. Commonly abused and their analysis of BZDs and their metabolite in urine has become important. A rapid solid phase extraction method using disposable pipette extraction (DPX) was developed. Using DPX with LC/MS/MS and GC/MS methods, high recoveries were found in the range from 71-99 %. LODs were less than 10 ppb for all BZDs (%RSD < 10%).

The screening for abused steroid with accurate analytes is needed in the horse racing industry. Noninvasive, rapid DPX method applied to urine samples with detection by LC/MS/MS was used for simultaneous screening and confirmation of anabolic steroids and corticosteroids. The range of mean recovery for both anabolic steroids and corticosteroids was 77-116%. The LOD and LOQ levels were less than 40 and 132 ppb, respectively.

Melamine and cyanuric acid have been identified as adulterants in milk and powdered infant formula, and this has become a major public health concern.

A rapid cleanup method using DPX was developed for simultaneous analysis of both analytes using GC/MS and GC/MS/MS. Recoveries were higher than 80%. LODs were less than 0.1 ppm with %RSDs less than 10% for both analytes. Manually routine analysis of pesticides and aflatoxin in agricultural products is tedious work. An automated QuEChERS method (quick, easy, cheap, effective, rugged and safe) was developed for rapid analysis of over 200 pesticides using GC/MS and LC/MS/MS with recoveries that ranged from 70-117% (%RSD<14 >%). An automated DPX followed by LC/MS/MS was used to analyze aflatoxin B1 with a recovery of 82% (%RSD of 8%). LOD and LOQ levels were 1.7 and 5.5 ppb, respectively.

Rights

© 2012, Pakritsadang Kaewsuya

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