Influence of the nature of the solvent on the extraction of cannabinoids from "Spice" plant matrices

Abstract

In late 2008, several synthetic cannabinoids were detected in herbal smoking mixtures for the first time in a few countries. These mixtures, named usually “Spice” are perhaps the best known examples of narcotics that from 2012 have been available globally. “Spice”-type products are smoked as an apparently legal alternative to cannabis but now became illegal in many countries. The matrix of “Spice” products often include a long list of different plants that contain in small quantities different synthetic cannabinoids or cannabimimetics. These plant matrixes are different in different countries. Many synthetic cannabinoids and their analogs after extraction from plant matrix are readily resolved and determined using gas chromatography and liquid chromatography with MS detector (GC-MS, LC-MS), but their identification and quantitative analysis is limited by the availability of their pure reference materials. The aims of this paper are to identify the main plant matrixes of the “Spice” products in Russia as well as to compare the efficiency of solvents for extraction of 18 representatives of cannabinoids and cannabimimetics. Ten solvents like acetonitrile, acetone, chloroform, methanol, ethanol, diethyl ether, hexane, heptane, octane, and toluene as well as mixture (1:1) of methanol and chloroform were used for testing the efficiency of cannabinoids extraction. To obtain the chromatographic and analytical data of cannabinoids, GC-MS analyses were performed on a Agilent 7820A gas chromatograph, coupled to a mass-selective detector Agilent 5975 (Agilent Technologies, USA). It was shown by anatomy-morphological investigation of about 1800 examples of “spices” that cammomile is the most often exploitable plant matrix for cannabinoids and cannabimimetics in Russia; the sage, marijuana, leaf tobacco, mixture of plants are used more rare and the most seldom use the blue cornflower. The extent of solvent extraction of 18 synthetic cannabinoids and cannabimimetics by different solvents from cammomile plant matrix was determined. It was shown that the most effective extractants are polar solvents like acetonitrile, acetone, chloroform, ethanol and methanol-chloroform mixture that provide the extraction extent of the cannabinoids in the interval 85-92%. It was established by using these solvents that the nature of plant matrix in most cases does not significantly influence on the extent of cannabinoid extraction from plant matrixes.