Identification and determination of synthetic cannabinoids in herbal products by dry film attenuated total reflectance-infrared spectroscopy.

A new procedure has been developed for the identification and quantitative determination of synthetic cannabinoids in illicit herbal preparations. The methodology is based on the use of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) measurement of sample extracts with 2-propanol drying 5µL of the extracts onto the ATR crystal. The qualitative identification was carried out on the 2-propanol extract after identification of the herbal matrix, followed by its subtraction and using a cut-off criterion of 75%. Quantitative determination was made by univariate calibration using the absorbance of the band located at 1520cm of the spectrum. Four different cannabinoids, RCS-4, JWH-210, UR-144 and JWH-081 were used as test analytes and the ATR-FTIR method provided limits of quantification from 14 till 79mgL. Sized blank market samples were successfully identified and UR-144 quantified.