Gas Chromatography-Mass Spectrometry Method for the Quantitative Identification of 23 New Psychoactive Substances in Blood and Urine.

New psychoactive substances (NPSs) have become an integral part of the recreational drug market with "new" compounds being reported by the European Monitoring Centre for Drugs and Drug Addiction weekly. Due to the changing nature of NPSs, it is impractical to carry out single analyte or even simple class quantitation. Although several gas chromatography-mass spectrometry (GC-MS) methods have been developed these are typically class specific. We present a validated GC-MS method for the quantitation of 2-DPMP, 3-MeO-PCE, 3-MeO-PCP, 5-APB, 6-APB, benzedrone, butylone, ethylone, flephedrone, methiopropamine, MDPV, mephedrone, methoxetamine, methylone, naphyrone, 25B-NBOME, 25C-NBOME, 25D-NBOMe, 25E-NBOME, 25H-NBOME, 25I-NBOME, Mescaline-NBOME and 25P-NBOME in blood and urine samples. Sample preparation was carried out using solid-phase extraction followed by derivatisation and analysis by GC-MS. Parameters investigated for validation included bias, precision, linear calibration model, carryover, interferences, limit of detection, limit of quantification, and autosampler and freeze/thaw stability. All drugs yielded successful results for each of these parameters as per SWGTOX guidelines. The GC-MS method was used for the reanalysis of 12 blood samples (eight cases) where 25I-NBOMe, 25C-NBOMe, methoxetamine and methylone had previously been detected by NMS laboratories. This GC-MS method was able to quantitatively detect these drugs in 75% of the blood samples, 42% of which contained either 25C-NBOMe or 25I-NBOMe. This method accurately allows for the simultaneous quantification of a wide variety of compounds via GC-MS, in particular NBOMe compounds which are typically analysed by liquid chromatography-tandem mass spectrometry which is not available in all laboratories.