Rapid isolation of acidic cannabinoids from Cannabis sativa L. using pH-zone-refining centrifugal partition chromatography.

This work introduces an effective methodology for the isolation of acidic cannabinoids from fiber-type Cannabis sativa L. Supercritical fluid extraction (SFE) was initially employed to obtain an enriched extract of acidic cannabinoids. Subsequently, fractionation was performed by using centrifugal partition chromatography (CPC) with the pH-zone-refining method. The biphasic solvent system that was selected consisted of n-hexane/ethyl acetate/ethanol/water 8:2:5:5 (v/v/v/v). Trifluoroacetic acid was added as retainer in the organic stationary phase, while triethylamine was used as eluter in the aqueous mobile phase. The most promising CPC fractions containing cannabidiolic acid (CBDA) and cannabidivarinic acid (CBDVA) were further purified by liquid-liquid extraction. Following this procedure, 1.86 g of CBDA (>85%) were recovered from 9 g of extract, with 1.08 g thereof having a purity of more than 95%, as determined by HPLC-PDA analysis. Moreover, 91 mg of CBDVA with greater than 85% purity were obtained. This methodology can be efficiently used for the large-scale purification of CBDA and after minor modifications could be readily adaptable for the isolation of other acidic cannabinoids, based on their ionizable character.