Advantages and limitations of spectroscopic, chromatographic and electrophoretic methods for the characterisation of synthetic cannabinoids and synthetic cathinone derivatives

Abstract

Over the last decade new psychoactive substances (NPS) flooded Europe and the challenging task for drug law enforcement is how to effectively respond to the dynamically and constantly changing drug market. NPS are regarded as legal alternatives to internationally controlled drugs of abuse. NPS are sold via the internet as, inter alia, “designer drugs”, “legal highs”, or “bath salts” in colourful and professionally designed packages mixed with herbal products or as pure powder. There is a persisting race between the legal prosecution and the producers of designer drugs as those strive to be one step ahead by rapidly generating new NPS products in reaction to new legislative measures. The rapid emergence of novel products means that developing and maintaining selective analytical methods and reference standards is challenging. Beside laboratory methods, the demand for portable analytics is high given the versatile distribution channels and the related particular risk for public institutions handling these products including postal delivery facilities, custom controls and prisons. In this thesis, new analytical methods were developed for the detection of synthetic cannabinoids and synthetic cathinones, the most frequently seized NPS subgroups. An ion mobility spectrometry (IMS) method was developed as an in-field alternative presumptive test for the non-destructive and selective detection of NPS in different matrices by wiping the surface of a sample with a swab. The suitability of the method for on-site analysis was demonstrated in a prison in Rhineland-Palatinate. The contactless and non-destructive detection of NPS was investigated using THz radiation for the first time. Fast characterisation of newly emerged and unknown substances was examined using portable and laboratory-based Raman spectrometers. Data analysis used a combination of a newly developed principal component analysis model and frequency tables. In addition, it was shown, that the analysis of herbal mixtures was possible using a simple solid/liquid extraction followed by precipitation of the synthetic cannabinoid constituents. New laboratory methods were developed to complement the screening techniques. The possibility to quantify NPS via the calibration curves of a small set of NPS, for which reference material is commercially available was demonstrated and validated via the analysis of seizures using ultra-performance liquid chromatography-diode array detection. Finally, capillary electrophoresis-diode array detection with a chiral selector was used for the chiral discrimination of NPS in the form of a general unknown screening method for mixtures and bulking agents on the one hand and a high throughput method for the fast analysis of single substances on the other hand. With the methods developed here, the analytical portfolio of NPS drug analysis was greatly expanded to meet the challenges of the dynamically and constantly changing drug market. All methods were successfully applied to real samples and partly in routine analysis in different criminal investigations offices and in public institutions (Wittlich prison).