Marijuana metabolites in urine of man. XI. Detection of unconjugated and conjugated delta 9-tetrahydrocannabinol-11-oic acid by thin-layer chromatography.

A method for separating unconjugated and conjugated delta 9-tetrahydrocannabinol-11-oic acid, the major urinary metabolite of delta 9-tetrahydrocannabinol in man, by liquid-liquid extraction and detection of both forms by thin-layer chromatography is described. The unconjugated form of the metabolite is extracted with hexane-diethylether (65:35), and the conjugated form (which remains in the aqueous phase) is extracted with ether after enzymic hydrolysis. The residue of each extract is chromatographed in an alkaline and an acidic solvent sequence, and the metabolites are detected with Fast Blue Salt B.