Abstract :
[en] Synthetic cathinones (SCs) are phenylalkylamine compounds related to natural cathinone from Catha Edulis leaves. Given their structural similarities with amphetamines, these compounds are mainly drugs of abuse. Indeed these substances constitute the second most frequently seized group of new psychoactive substances (NPS) and counted more than 130 compounds in Europe (EMCDDA 2016). In addition to be sold on the illegal market, some of them are currently available online using various brand names as “bath salts”, taking advantage of a legislative void. In this context, reliable analytical tools are required to track these substances.
In this study, our goal was to develop a capillary electrophoresis separation method coupled to laser induced fluorescence detection (CE-LIF) to analyze most frequently observed SCs. As these stimulants are frequently used as substitutes to these drugs, most common amphetamines were also included.
Due to their lack of native fluorescence, analytes were labeled using fluorescein isothiocyanate isomer I (FITC) using a previously developed protocol adapted to small basic compounds. Then, various BGE composition and additives were investigated in order to optimize the separation. As the Brij 35, a non-ionic surfactant, showed interesting selectivity, the development of a micellar electrokinetic capillary chromatography (MEKC) method was performed. Brij 35 concentrations as well as its mixture with ionic, non-ionic surfactants, cyclodextrines and different organic solvents were investigated in order to achieve the separation of these closely related compounds.
Finally, a FITC labeling protocol adapted to SCs was optimized in terms of sensitivity and repeatability using design of experiment (DoE) strategy. Critical parameters highlighted previously, FITC/analyte ratio, pH of reaction buffer and reaction time were investigated. Multivariate analysis helped to define optimal labeling conditions.
In the growing and evolving field of NPS analysis, we are now able to propose a generic MEKC-LIF method for the screening of SCs.
