Magnetic Solid Phase Extraction: a new method for the determination of synthetic cannabinoids in hair

New psychoactive substances (NPS) are substances often known as either designer or synthetic drugs, or by the more popular term of ‘legal highs’. They are analogues of existing controlled drugs and pharmaceutical products or newly synthesised chemicals, created to mimic the actions and psychoactive effects of licensed medicines and other controlled substances. Synthetic cannabinoids (SC) first formally identified and reported to the EMCDDA in 2008, initially being used as alternatives to herbal cannabis, particularly to avoid detection in those settings with forensic drug testing regimes. To date, SC represent the largest and most structurally diverse class of NPS [2]. A fast and inexpensive detection of these class of drugs in biological samples is of utmost importance to monitor their diffusion since SC have proliferated worldwide in many different structures, forms and potencies. The choice of the matrix to be investigated depends on the purpose of the analysis. Hair testing has gained increasing attention since it is a unique material for the retrospective detection of drugs, due to its large detection window. The extraction of SC from the inner of the hair structure is a critical point as well as the clean-up of hair extracts. Different strategies have been proposed for this purpose. Hair incubation is often performed by digestion of the hair matrix with NaOH; or by the incubation of hair with methanol or other solvents for several (4 to 18) hours. Clean-up is crucial in both cases and usually can be performed by classic liquid-liquid extraction (LLE) or solid phase extraction (SPE). The main issue is the lack of versatility of all these techniques if compared with the breadth of analytes that should be considered. In recent years magnetic-solid phase extraction (MSPE), which is based on the use of functionalised magnetic nanoparticles for dispersive SPE, is gaining interest in various fields, but its application in forensic and toxicological field is currently underdeveloped. The aim of this study is the development of a new protocol for qualitative and quantitative determination of several SC in hair. Drug extraction from hair was performed by means of MeOH incubation followed by a MSPE clean-up. Magnetic particles were synthesized according to Yu et al. [3], with a slight modification, and functionalized with a C18 shell. Particles shape and functionalization was characterised by means of FT-IR, TEM and SEM analyses. Preliminary results showed good recoveries for all selected analytes and a remarkable clean-up efficiency. The protocol has been validated following national and international guidelines.