[Gas chromatographic analysis of cannabinoids on tandem columns]

A simple, isotherm packed column gas chromatographic method was developed for the quantitative determination of neutral cannabinoids using 4-androstene-3,17-dion as internal standard. In order to achieve the best resolution and to avoid the evaluation of the disturbing hydrocarbon peaks a method was developed using "tandem" column made of 3% OV-1 (90%) and 3% OV-17 (10%) stationary phases. The psychotropic cannabinoids delta 1-tetrahydrocannabinol (delta 1-THC) and delta 1(6)-tetrahydrocannabionol (delta 1(6)-THC), as well as, their main metabolites cannabidiol (CBD) and cannabichromene (CBC) were baseline separated except the cannabigerol (CBG) and cannabinol (CBN) pair, however for these compounds the separation was also satisfactory for the quantitative determinations. The Kováts retention indices were calculated for the most important cannabinoids and established the detection limits, respectively (20-50 ng range). The reproducibility was found excellent cv% = 1.06 for delta 1-THC and the analysis time was 55 minutes. The practical usefulness of the method was demonstrated by the comparative analyses on hashish- and fibre type hemps.