Development of Heated Headspace Solid Phase Microextraction-Gas Chromatography/Mass Spectrometry for Chemical Profiling of Marjuana

As submitted by the proposer: Chemical forensics is a nascent field that collects and attributes chemical information of physical evidence to their sources. Ideally, from a chemical forensic analysis, one can identify chemical signatures of physical evidence and use them to classify or trace the source of it. We propose to use heated headspace solid phase microextraction coupled to gas chromatography/mass spectrometry (HHS-SPME-GC/MS) as an analytical platform for the collection of chemical signatures of physical evidence. To prove this concept, we will collaborate with the Southwest Regional Science Center (SWRSC) with the Department of Homeland Security on chemical profilingof marijuana samples using HHS-SPME-GC/MS. Marijuana is one of the most common controlled substances not only in the United States, but also worldwide. It is of forensic interests to trace the origin of marijuana for the purpose of criminal investigation. Many studies have demonstrated the use of chemical profile analysis for the classification of marijuana samples. The chemical profile has been reported as a fingerprint for the source of marijuana. Unfortunately, there is no standardized chemical profiling method for marijuana to create a shared knowledge database. Also, many crime laboratories are not equipped with stable isotope ratio mass spectrometer analysis (IRMS) to perform IRMS analysis. Therefore, we propose to develop an alternative instrumentation using a solvent free extraction method to extract signature chemicals from marijuana sample. After extraction, the detection of the chemical signatures will be performed with a GC/MS, which is a basic and common analytical instrument in most crime laboratories. The HHS-SPME-GC/MS methodology can be easily adopted, because the acquisition cost of hardware are minimal. With this development, we envision the marijuana caseload can be reduced, due to automated HHS-SPME technique. Also, a standard chemical profile method for marijuana samples can be established with this sensitive, robust and rugged HHS-SPME-GC/MS methodology, by which a global marijuana chemical database can be shared between crime laboratories. We expect this new analytical platform will greatly improve the classification of marijuana samples seized from different origins. Our long term goal is to apply the HHS-SPME-GC/MS analytical platform to profile and establish databases for a variety of trace evidence, such as fiber, designer drug, synthetic weed, fire debris, polymers, duct tapes, gun powders, explosive residues, just to name a few. Manuscripts describing the optimization of the HHS-SPME-GC/MS will be submitted to peer reviewed journals. A final technical report will be submitted to NIJ for publication in order to disseminate the development of automated HHS-SPME-GC/MS for forensic applications.
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