Micellar electrokinetic chromatography: A new simple tool for the analysis of synthetic cannabinoids in herbal blends and for the rapid estimation of their log P values

For the first time a capillary separation based on micellar electrokinetic chromatography (MEKC) with diode array detection (DAD) was developed and validated for the rapid determination of synthetic cannabinoids in herbal blends. Separations were carried out on a 30 μm (ID) × 40 cm uncoated fused silica capillaries. The optimized buffer electrolyte was composed of 25 mM sodium tetraborate pH 8.0, 30 mM SDS and n-propanol 20% (v/v). Separations were performed at 30 kV. Sample injection conditions were 0.5 psi, 10 s. Diazepam and JWH-015 were used as internal standards. The determination of the analytes was based on the UV signal recorded at 220 nm, corresponding to the maximum wavelength of absorbance of the molecules, whereas peak identification and purity check were also performed on the basis of the acquisition of UV spectra between 200 and 400 nm wavelengths. Under the described conditions, the separation of the compounds was achieved in 25 min without any significant interference from the matrix. Linearity was assessed within a concentration range from 5 to 100 μg/mL. The intra-day and inter-day imprecision values were below 2.45% for relative migration times and below 10.75% for relative peak areas. The present method was successfully applied to the direct determination of synthetic cannabinoids in 15 different herbal blend samples requiring only sample dilution. In addition, the developed MEKC separation was also applied to estimate the octanol/water partition coefficients (log P) of these new and poorly known molecules.

► We developed a CE separation based on MEKC for the determination of ten synthetic cannabinoids in clandestine preparations of “Spice” products.
► To the best of our knowledge, the present is the first report on the application of CE/MEKC to the analysis of the JWH class of compounds.
► The method was fully validated and applied to the quantitative analysis of synthetic cannabinoids in 15 real samples of clandestine preparations (Spice products).
► The MEKC separation was also used to estimate the log P values of these new compounds.