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Abstract
Forensic laboratories are tasked with the identification of drugs like fentanyl using different confirmatory methods. Herein we report the efficacy of the identification of fentanyl-related substances (FRS) using GC-MS and GC-IR confirmation by way of newly constructed fentanyl libraries. Additionally, the utility of these libraries to the forensic community was validated through interlaboratory studies from seven (7) forensic laboratories. The efficacy of GC-MS and GC-IR for the confirmation of a small sample of phytocannabinoids and synthetic cannabinoids were also investigated. Finally, the use of MassWorks™ software to generate high resolution spectra from single quadrupole GC-MS was be explored in conjunction with high resolution QTOF-MS/MS.
New GC-MS and GC-IR libraries were created for 212 FRS and are now freely available to the forensic science community. A library search of each of the 212 FRS using the NIST library produced 4.7% matches to the correct compound, which is not unexpected as most of the FRS were not included the NIST library. In contrast, 89.6% of the searches resulted in the correct compound within the top five candidates when using the newly created GC-MS library. Finally, when the new GC-IR library containing all 212 FRS was searched, 100% identification was achieved.
The results of the interlaboratory study showed improvement in identification of the FRS in question, increasing from ~75% using GC-MS to 100% correct when using vapor phase GC-IR analysis.
Phytocannabinoids fragment during GC-MS to produce easy to differentiate mass spectra. However, isomeric compounds of the synthetic cannabinoids resulted in some isomers being misidentified with those having similar mass spectra. This problem was resolved with the utilization of the GC-IR spectra.
In an effort to obtain high-resolution mass spectral data for fentanyl from single quadrupole GCMS data, MassWorks™ software was utilized. The accurate mass reported for the MassWorks™ data is often a fraction less than the actual value; while those generated by the high-resolution instrument are often a fraction more than the actual value. However, since the fentanyls only sparsely produce molecular ions with GC-MS, it is more useful to analyze using ESI-QTOF-MS/MS, where the molecular ion can be generated and analyzed.