Enantioseparation performance of superficially porous particle vancomycin-based chiral stationary phases in supercritical fluid chromatography and high performance liquid chromatography; applicability for psychoactive substances.

Novel psychoactive substances (NPS) are synthetic compounds that have been designed to produce the physiological and psychological effects of known recreational drugs, while circumventing current drug control laws and scheduling guidelines. Such "designer drugs" pose problems in detection and prevention of use, and they are no less dangerous than known controlled substances. Among the various classes of NPS, many are chiral. As they are synthetic products, most are racemates. Not unexpectedly, there is limited information about different the pharmacological and toxicological properties of their pure enantiomers. Hence, fast and reliable enantioselective methods are of great interest. In this work, superficially porous particle (SPP) vancomycin-based chiral stationary phases were used for development of fast enantioselective separation methods for various classes of NPS in supercritical fluid chromatography and liquid chromatography. The NPS tested included pyrovalerones, benzofurans, phenidines and phenidates. The effect of mobile phase composition on the retention and resolution of NPS in supercritical fluid chromatography was examined. The amount as well as the ratios of additives used is crucial for enantioseparation efficiency. Results showed the high enantioselective potential of vancomycin-based columns in both chromatographic techniques; 88% of NPS tested were enantioseparated in supercritical fluid chromatography and 69% of NPS tested were enantioseparated in liquid chromatography. Moreover, under optimized conditions, simultaneous enantioseparations of some NPS were achieved, which indicates great suitability of vancomycin-based columns for this purpose. The proposed methods can serve as guides for method development and for enantioseparation of further upcoming NPS.

Successful use of a novel lux® i-Amylose-1 chiral column for enantioseparation of "legal highs" by HPLC.

Bath salts, fumigations, cleaners and air fresheners, behind these terms substances are hidden, which count as "Legal Highs". These fancy names are used to pretend Legal Highs as harmless compounds, to circumvent legal regulations for marketing as well as to increase the sales. Besides classic illicit drugs of synthetic origin such as amphetamines, cocaine and MDMA, the trade of these compounds, also known as new psychoactive substances (NPS), is not uncommon today. In many countries, NPS are still not subject to drug control. Among them, there are stimulants such as new amphetamine derivatives or cathinones, which possess a chiral centre. Little is known about the fact that the two possible enantiomers may differ in their pharmacological effect. The aim of this study was to test a novel HPLC column for the enantioseparation of a set of 112 NPS coming from different chemical groups and collected by internet purchases during the years 2010-2018. The CSP, namely Lux® 5 µm i-Amylose-1, LC Column 250 x 4.6 mm, was run in normal phase mode under isocratic conditions, UV detection was performed at 245 nm and 230 nm, injection volume was 10 µl and flow rate was 1 ml/min. With a mobile phase consisting of n-hexane/isopropanol/diethylamine (90:10:0.1), herein, 79 NPS were resolved into their enantiomers successfully, for 37 of them baseline resolution was achieved. After increase of lipophily of the mobile phase to 99:1:0.1, another 27 compounds were baseline separated. It was found that all separated NPS are traded as racemic compounds.

Separation of enantiomers of new psychoactive substances by high-performance liquid chromatography.

New psychoactive substances are defined as compounds with consciousness-changing effects and have been developed simultaneously with classical drugs. They arise through structural modifications of illegal substances and are mainly produced to circumvent laws. Availability is simple, since new psychoactive substances can be purchased from the Internet. Among them many chemical drug compound classes are chiral and thus the two resulting enantiomers can differ in their effects. The aim of this study is to develop a suitable chiral high-performance liquid chromatography separation method for a broad spectrum of new psychoactive substances using cellulose tris(3,5-dichlorophenylcarbamate) as a chiral selector. Experiments were performed by high-performance liquid chromatography in normal-phase mode under isocratic conditions using ultraviolet detection. Direct separation was carried out on a high-performance liquid chromatography column (Lux® i-Cellulose-5, 3.5 µm, Phenomenex®), available since 2016. Excellent separation results were obtained for cathinones. After further optimization, even 47 instead of 39 out of 52 cathinones showed baseline separation. For amphetamine derivatives, satisfactory results were not achieved. Further, new psychoactive substances from other compound classes such as benzofuranes, thiophenes, phenidines, phenidates, morpholines, and ketamines were partially resolved, depending on the polarity and degree of substitution. All analytes, which were mainly purchased from the Internet, were proven to be traded as racemates.

Indirect chiral separation of 8 novel amphetamine derivatives as potential new psychoactive compounds by GC-MS and HPLC.

Amphetamine and its derivatives gained high popularity on the illegal drug market. In the last few years, a lot of new psychoactive compounds structurally related to amphetamine, such as 4-fluoroamphetamine and 4-fluoromethamphetamine swamped the drug market. They were designed to circumvent prohibition of amphetamine and N-methylamphetamine and are distributed via the Internet. Often, a halogen atom is introduced into the phenyl ring of amphetamine to turn the illegal amphetamine legal. Since amphetamines possess a chiral centre, two enantiomers are available, which might differ in activity. Since most of them are partially not commercially available to date, synthesis and characterisation of amphetamine derivatives might help authorities to identify these substances of abuse. The aim of this study was to investigate self-synthesized amphetamines concerning their identity and their enantiomeric status either by GC-MS or by HPLC. For GC-MS, derivatization with (R)-(+)-α-methoxy-α-trifluoromethylphenylacetic acid (MTPA) or (1R)-(-)-menthylchloroformate prior to analysis on a HP-5MS column was done. For chiral separation by HPLC a LiChrospher 100 RP-18e column and sulfated beta-cyclodextrin added to the mobile phase as chiral selector were used. Enantioseparation was accomplished successfully by both methods. Furthermore, simultaneous chiral separation of three positions isomers, namely 2-fluoroamphetamine, 3-fluoroamphetamine and 4-fluoroamphetamine, was shown successfully by HPLC.