Semester of Graduation

Fall 2025

Degree

Master of Science (MS)

Department

Chemistry

Document Type

Thesis

Abstract

A forensic sampling system was developed for extraction of material from surfaces for off-line analysis by mass spectrometry. The system is composed of a pulsed valve and vacuum aspirated capture with a membrane filter. Particles are deposited on a surface that contains the analyte of interest and the pulsed valve displaces the particle and analyte mixture that is captured on the filter. The material is extracted from the filter and analyzed by mass spectrometry. The sampling system was utilized to capture from the surface of brick, paper, carpet, fabric (90:10 polyester cotton fabric) and glass. Gas chromatography/mass spectrometry (GC-MS) data verified recoveries of caffeine from the surfaces and the detection limit on glass was found to be less than 1 µg. The sampling system was also used to extract ignitable liquids in simulated arson studies. Porous, non-porous and functionalized nanoparticles were used as extraction particles for gasoline and diesel fuels. GC-MS confirmed the presence of ignitable liquid materials and statistical analysis was used to assess components in burned matrices. Using functionalized C18 particles and porous nanoparticles as extraction particles, gasoline traces were identified. The signal intensity was four times as intense when using functionalized C18 particles compared to porous nanoparticles suggesting a more selective capture of specific ignitable liquids with the C18 particles. A portable system was also developed that utilizes inexpensive components. The system utilizes an automobile fuel injection valve and a compressed air canister, and a portable vacuum for sampling. The system is powered by a 12v lead-acid battery. The prototype design was used to extract small molecules from several surfaces at recoveries comparable to the laboratory pulsed valve sampling and performed better than swab based sampling on porous surfaces.

Date

7-12-2025

Committee Chair

Murray, Kermit K.

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