Enantioselective separation of Novel Psychoactive Substances using a Lux® AMP 3 μm column and HPLC-UV

Abstract

The abuse of Novel Psychoactive Substances (NPS) still cause severe problems. A lot of them contain a stereogenic centre which leads to possible different pharmacological effects of the enantiomers.The aim of this study was to establish an enantioselective HPLC-UV method with applicability to a broad spectrum of NPS. Different compound classes including mainly amphetamines, cathinones, ketamines, pyrovalerones and benzofuries were tested for successful enantioseparation by one common chromatographic condition. All NPS samples were bought in various internet stores, were sythesized inhouse or were seized by the Austrian police. A commercially available Phenomenex LUX® AMP 3 μm, 150 × 4,6 mm column served as chiral stationary phase (CSP) for the enantiomeric separation experiments. This CSP has been developed particularly for enantioresolution of high abundant synthetic chiral drugs such as MDMA and amphetamine. All measurements were performed under isocratic conditions. For method optimisation, the effects of different mobile phase compositions, different pH values and temperatures on enantioseparation were investigated. Final mobile phase consisted of ammonium bicarbonate solution (5 mM) adjusted with concentrated ammonia to a pH of 11.3 mixed with acetonitrile in a ratio of 70:30. All in all, 83 of 95 analysed NPS were separated in their enantiomers successfully within 40 min. Furthermore, the method was found to be suitable for simultaneous enantioseparations, for enantiomeric elution order determinations, enantiomeric purity checks and for positional isomer separations. To prove the repeatability of the method, an intra- and an interday validation was performed successfully. By means of the wide applicability of the chosen column all separated NPS were shown to be traded as racemic mixtures.