This study investigated a number of novel derivatization schemes that might improve mass spectral analysis of synthetic cathinones , an important class of designer drugs within the United States, using gas chromatography/mass spectrometry (GC/MS), which is the most widely used technique in forensic toxicology laboratories.
Cathinones, particularly the pyrrolidine-type (or tertiary amine) drugs within this class, undergo extensive fragmentation in electron impact (EI) ionization, yielding relatively poor quality mass spectra. Derivatization is commonly used to address this problem. The current study found that although derivatization is a common approach for improving thermal stability and mass spectral properties, the chemistry of these polyfunctional drugs is inherently more complex than their non-ketone counterparts. A number of derivatization schemes found that although functionalization of the ketone was possible, the products had a number of drawbacks. Given the potential for thermal instability during GC/MS and the need for sensitivity in forensic toxicology determinations, alternative analytical techniques such as LC/MS, LC/MS/S or LC-q-TOF might be preferable for the determination of synthetic cathinones in biological evidence. Factors influencing the thermal degradation of synthetic cathinones were investigated. In-situ degradation was minimized using lower temperatures, decreasing residence time in the inlet, and eliminating active sites. Although thermal degradation was minimized, these factors should be carefully considered during method development, validation, and routine testing of cathinones by GC/MS. 42 figures, 18 tables, and 137 references