Analysis of synthetic cannabinoids in herbal blends by means of nano-liquid chromatography

In this study, a rapid and simultaneous separation of 12 synthetic cannabinoids and Δ(9)-tetrahydrocannabinol (Δ(9)-THC) in herbal blends was obtained by means of nano-liquid chromatography (nano-LC). The nano-LC experiments were performed in a 100μm i.d. capillary column packed with Cogent(®) bidentate C(18) silica particles for 25.0cm. All compounds were resolved using an isocratic elution mode in less than 30min. A mobile phase containing ACN/MeOH/H(2)O/formic acid 69/5/25/1 (v/v/v/v) was employed for the chromatographic separation. The developed analytical method was validated in terms of precision, linearity, sensitivity and accuracy. Under optimal nano-LC-UV conditions, the resulting RSD percentages for intra-day and inter-day repeatability, related to retention time and peak area, were below 2.98 and 6.40%, respectively. Limits of detection and quantification were 0.2 and 0.5μg/mL, respectively, for all the studied compounds. Linearity was assessed in the concentration range of interest for all analytes with determination coefficients r(2)≥0.9975. The method was then applied to the determination of synthetic cannabinoids in herbal blends. Quantitative analyses of the cannabimimetic compounds in six products showed that there was a wide difference in the concentration of the studied compounds among different products. Further, the nano-LC system was coupled with a mass spectrometer measuring the MS and MS-MS spectra to unequivocally identify the cannabinoids present in smoking mixtures.