Date of Award

1-1-2011

Document Type

Campus Access Dissertation

Department

Chemistry and Biochemistry

Sub-Department

Chemistry

First Advisor

Stephen L Morgan

Abstract

Textile fibers found at crime scenes as trace evidence often provide leads or confirmations in criminal investigations. The development of analytical techniques for forensic discrimination of fibers by micro-extractions of dyes followed by liquid chromatography (LC) or capillary electrophoresis (CE) with UV/visible diode array (DAD) or mass spectrometric (MS) detection is described. Separation and characterization of acid, basic and disperse dyes from nylon, acrylic and polyester fibers was achieved. Ultra performance liquid chromatography with DAD detection provided quantitative estimates of dye amounts, UV/visible spectra for dye characterization, and information on dye formulations. Foremost, LC/MS/MS used multiple reaction monitoring (MRM) transitions unique for every dye molecule allowing unequivocal discrimination between fibers as short as 0.5 mm in length and limits of detection for this method range between 200 and 1500 pg for most dyes. CE/DAD methodology characterized of fluorescent brighteners extracted from millimeter threads of white fibers. The analysis of environmentally exposed fibers by LC/MS revealed the loss of dyes from textiles, the addition of extraneous contaminants that contribute to the interpretation of degradation effects on fiber evidence and determination of their forensic relevance.

Novel sample preparation techniques for the analysis of drugs of abuse in biological

matrices using disposable pipette extraction (DPX) are described. DPX uses a loosely extraction sorbent contained inside of a pipette tip allowing dynamic mixing with the sample and selective elution of analytes. Whole blood samples were treated by DPX to remove matrix components that potentially interfere with liquid chromatographic analysis. Extracts were then analyzed by LC/MS/MS for comprehensive screening of over 40 pain management drugs and metabolites. The extraction of anabolic steroids from low volume of urine samples using DPX followed by gas chromatography/ mass spectrometry (GC/MS) analysis is also described. Recoveries of most of the drugs analyzed in blood and urine were 85 % or greater with relative standard deviations less than 10 % and LOQs in the low ng/mL range. Finally, an analytical chemistry undergraduate laboratory experiment was developed using DPX as a teaching tool for quantitative analysis of caffeine in soft drinks with UV/visible spectrophotometry and GC/MS.

Rights

© 2011, Oscar Gilberto Cabrices

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