Separation of enantiomers and positional isomers of novel psychoactive substances in solid samples by chromatographic and electrophoretic techniques - A selective review.

Novel Psychoactive Substances (NPS) represent an alternative to established illicit drugs. They are traded via the internet and exhibit small alterations in their chemical structure to circumvent law, however, their psychotropic effects are comparable. There is still poor knowledge about side effects and health risks. By the end of 2018, 730 NPS were reported to EMCDDA (European Monitoring Centre for Drugs and Drug Addiction). Among different compound classes, many NPS are chiral and few publications deal with the different pharmacological and toxicological properties of their pure enantiomers. Therefore, analytical method development concerning enantioseparation of NPS is of great interest. Chiral separation protocols of established illicit drugs have been transferred for NPS, selected examples are given as well. Different methods for enantioseparation of NPS comprising mainly stimulating drugs such as cathinones, pyrovalerones, amphetamines, ketamines, (2-aminopropyl) benzofuranes, phenidines, phenidates, morpholines and thiophenes are reviewed. Moreover, chiral resolution of some cannabinomimetics by HPLC is presented. Chromatographic and electrophoretic techniques such as GC, HPLC, SFC, CE and CEC are discussed and in some cases compared. Mainly, solid samples either purchased from internet vendors, seized by police or collected from patients in hospitals are subject to analysis. Chiral selectors used for HPLC are listed in a Table. It was shown that particularly stimulating drugs are traded as racemic mixtures, which is not the case with cannabinomimetics. Mainly, HPLC and CE were used for enantioseparation of NPS.