Synthetic Cannabinoids: general aspects and screening analysis by HPLC-UV-Fl technique

Synthetic cannabinoids (SC) represent a very important side of the emerging and worrying phenomenon of the New Psychoactive substances (NPS). Currently, the determination of SC is based on the use of LC/GC – MS techniques. Although this analytical approach have been successfully applied to the determination of SC in both clandestine preparations and biological fluids, it is expensive and usually not suitable for the screening analysis in routine laboratories. Aim of this work was the development of a method based on a HPLC separation associated with a UV and FL detection, for the determination of SC in herbal mixtures. The experiments were performed using a HPLC-UV-FL system [LC-10AD HPLC Pump (Shimadzu, Tokio); Jasco 875-UV Intelligent Spectrophotometric detector (Jasco, Japan); RF10XAL Fluorescence detector (Shimadzu, Tokio)]. A reversed phase C18 column [Discovery, 150 mm x 4.6 mm, 3 μm, (Supelco, PA, USA)] was employed. The Communication Bus Module was a CBM-20A Prominence (Shimadzu) and the program on PC was “LabSolution” (2008-2010, Shimadzu Corporation). The separation was isocratic with a mobile phase composed by MEOH/H2O (87,20/12,80, v/v); the flow was set at 1 ml/min; the pressure was ≈ 200 bar. After optimization the best UV absorption scored at 229 nm, while, for the majority of the compounds, the best fluorescence signal was obtained at excitation wavelength = 350 nm and emission wavelength = 425 nm. The sample preparation of herbal mixtures was based on a simple extraction procedure (≈20 mg of sample incubated o.n. in 2 ml of MEOH at room temperature). Under the described conditions, nine SC were separated within 10 minutes with the following elution sequence: JWH-200, AM-694, JWH-015, JWH -250, JWH-073, JWH-018, JWH-081, JWH-019, JWH-210. Linearity was tested in the 1-10 µM concentration range. The analytical sensitivity ranged from 5.94 ng/ml (JWH-081) to 21.28 ng/ml (JWH-073). The method was successfully applied to the analysis of herbal mixtures seized at Smart Shops.