Comparative studies on enantioseparation of New Psychoactive Substances using cyclodextrin-assisted capillary electrophoresis with UV detection

Abstract

New psychoactive substances (NPS) count as psychoactive substances, which are slightly modified compared to illicit drugs regarding their chemical structure to circumvent law. Compared to classical drugs such as heroin, cocaine, or amphetamine, they show similar psychoactive effects, however, because of their novelty there is few knowledge about their side effects or toxicity. NPS are available as different chemical substance classes, among them chiral novel derivatives of amphetamine, cathinone, and ketamine. Since in most cases no clinical studies are available about the possibly different effects of the two enantiomers, there is a big demand for enantioseparation method development. Besides high-performance separation techniques such as gas chromatography or HPLC, capillary electrophoresis has turned out to be a powerful alternative for chiral separation development. The addition of chiral additives such as cyclodextrins to the background electrolyte often results in successful attempts. The present study compares the chiral separation power of different previously used non-charged ß-cyclodextrins, among them native ß-cyclodextrin as well as some of its derivatives such as acetyl-, and 2-hydroxypropyl-β-cyclodextrin, with the negatively charged derivatives carboxymethyl-, carboxyethyl- and succinyl-β-cyclodextrin by capillary zone electrophoresis. A total of 136 chiral NPS were investigated with these cyclodextrins, 122 of them were resolved in their enantiomers successfully by means of a simple electrolyte composition consisting of 10 mM aqueous sodium hydrogen phosphate buffer, pH 2.5 and 10 mM of the chiral selector. Furthermore, the presented method turned out to be useful to distinguish between positional isomers and examples for both enantiomer order and positional order for seized samples are given.