Discrimination of synthetic cathinones by GC-MS and GC-MS/MS using cold electron ionization

Gas chromatography-mass spectrometry is currently among the methods of choice for the analysis of synthetic cathinones. However, these analytes are extremely labile, and classical electron ionization (EI) results in excessive and relatively uninformative fragmentation, yielding little to no molecular ions. Cold EI reduces the internal energy of the analytes by expansion of supersonic molecular beams prior to their ionization, leading to improved molecular ion information. In this study, classical and cold EI were compared for the analysis of synthetic cathinones. We demonstrated that cold electron ionization produced enhanced molecular ion intensity for most of the bath salts considered, as well as more informative fragmentation. Principal component analysis showed that cold EI mass spectra are more discriminative than those obtained by classical EI. MS/MS can offer improved confidence in synthetic cathinone identification even in cases where the relative intensity of the molecular ion is very low in MS spectra.