Separation of cannabinoids on three different mixed-mode columns containing carbonanodiamond/amine-polymer superficially porous particles

摘要

Three mixed-mode high-performance liquid chromatography columns packed with superficially porous carbonanodiamond/amine-polymer particles were used to separate mixtures of cannabinoids. Columns evaluated included: (i) reversed phase (C-18), weak anion exchange, 4.6 x 33 mm, 3.6 mu m, and 4.6 x 100 mm, 3.6 mu m, (ii) reversed phase, strong anion exchange (quaternary amine), 4.6x33 mm, 3.6 mu m, and (iii) hydrophilic interaction liquid chromatography, 4.6 x 150 mm, 3.6 mu m. Different selectivities were achieved under various mobile phase and stationary phase conditions. Efficiencies and peak capacities were as high as 54 000 N/m and 56, respectively. The reversed phase mixed-mode column (C-18) retained tetrahydrocannabinolic acid strongly under acidic conditions and weakly under basic conditions. Tetrahydrocannabinolic acid was retained strongly on the reversed phase, strong anion exchange mixed-mode column under basic polar organic mobile phase conditions. The hydrophilic interaction liquid chromatography column retained polar cannabinoids better than the (more) neutral ones under basic conditions. A longer reversed phase (C-18) mixed-mode column (4.6 x 100 mm) showed better resolution for analytes (and a contaminant) than a shorter column. Fast separations were achieved in less than 5 min and sometimes 2 min. A real world sample (bubble hash extract) was also analyzed by gradient elution.