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Date of Award
Thesis and Dissertation-ISU Access Only
Master of Science (MS)
Department of Chemistry
Christopher C. Mulligan
The creation and proliferation of new psychoactive substances (NPS) over the last decade has shown that current forensic evidentiary screening methods are ineffective at identifying new compounds entering the market. The frequency and complexity of new drug evidence points to the need for robust screening methods, particularly portable instrument-based technologies that could expedite legal investigations and reduce the burden on the crime laboratory system. Direct sampling, field portable mass spectrometers (MS) coupled with ambient ionization methods have the potential to combat the NPS problem and alleviate the current evidentiary backlog by employing high-throughput, on-site analysis via automated identification.
The objectives of the validation and application studies described in this thesis support the implementation of an ambient-sampling, portable MS system featuring interchangeable, ambient ionization sources for high-throughput, on-site drug evidence screening. A comprehensive analytical validation was demonstrated by assessing selectivity, accuracy/precision, method robustness and ruggedness. Reliability in the form of false positive/negative response rates determined from large datasets is reported, examining the effect of user training, experience level, and environmental factors stemming from field usage. Furthermore, the applicability toward NPS evidence is demonstrated by characterizing a selection of structurally-similar substituted phenethylamines and implementing collected data for an on-board chemical library. Newly developed chemical libraries featuring automated identification capabilities were used for investigating complex mixtures, surface bound residues, and mock blotter paper evidence.
Lawton, Zachary Earl, "Analytical Validation of a Portable Mass Spectrometer System for High Throughput Forensic Screening" (2016). Theses and Dissertations. 622.
Available for download on Wednesday, February 10, 2027