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  • Combining Gas Chromatography-Mass Spectrometry and Principal Component Analysis to Facilitate Complete Detection and Identification of Ignitable Liquids
Title: Combining Gas Chromatography-Mass Spectrometry and Principal Component Analysis to Facilitate Complete Detection and Identification of Ignitable Liquids
This paper reports an approach that developed instrumental parameters with two different GC-MS instruments. Data from the two devices were combined with principal component analysis (PCA) to analyze genuinely and ignited ignitable liquid residues (ILR). We simulate the field samples by burning seasoned pinewood soaked with each ignitable liquid (IL). Enough unburnt components from an IL remained on the burnt wood. These components were enough to reveal the chromatographic fingerprint of an IL. Most importantly, the chromatographic profile from a pure IL and IL poured onto a wooden substrate and ignited was identical. The chromatographic profiles reported from each instrument for each IL were reproducible to within 3% RSD. The MS data from both GC-MS instruments showed similar m/z peaks from all ILs, indicating similar hydrocarbon(s) and or fragmentation cluster patterns in the ILs studied ingredients. The PCA data showed characteristic differences giving rise to the separation between incendiaries, albeit some were overshadowed by clustering. In some cases, ILs that showed similar components in their mass spectra profile grouped as a class on the PCA display. We demonstrate an approach using direct headspace injection to individualize ILs recovered from crime scenes. Direct headspace injection and GC-MS combined with PCA are shown as promising facile methods for the qualitative determination of specific ILs in real-world arson samples. Initially, our project started as an undergraduate instrumental analysis guided-inquiry (GI) project. Such labs have been reported to enhance student learning and improve students' critical and problem-solving abilities. We plan to incorporate this approach in both an undergraduate instrumental analysis class and a graduate-level analytical chemistry class.  more » « less
Award ID(s):
1900124
PAR ID:
10328296
Author(s) / Creator(s):
Editor(s):
Henry Charlier
Date Published:
Journal Name:
The chemical educator
Volume:
27
ISSN:
1430-4171
Page Range / eLocation ID:
33-43
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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