Introducing Headspace Gas Chromatography–Mass Spectrometry to Undergraduate Chemistry Students from a Forensic Toxicology Perspective

Headspace gas chromatography–mass spectrometry (headspace GC-MS) is a gold standard for identifying and confirming volatile compounds. This laboratory experiment introduces gas chromatography, mass spectrometry, and other important instrumental concepts and theories that apply to many disciplines of chemistry. This is achieved through the analysis of commonly targeted volatile compounds in forensic toxicology laboratories including ethanol, isopropanol, 1,1-difluoroethane, and acetone. This experiment is suitable for a wide variety of chemistry courses and addresses multiple learning outcomes, including those related to hands-on batch sample preparation and analytical data processing. Students are tasked with preparing aqueous calibrators and controls to determine the concentration of ethanol and the presence or absence of qualitative analytes in a simulated vitreous humor sample. Students then objectively evaluate the data through complex analysis methods using acceptance criteria. This experiment was conducted in a Forensic Toxicology course over three Spring semesters, with over a 92% success rate of students reporting accurate results. This experiment is easily adjustable based on student skill level, number of students, and resources available. Headspace GC-MS as an analysis tool also offers the benefits of minimal sample preparation and minimal instrument maintenance compared with GC-MS with liquid sampling and liquid chromatography–mass spectrometry.