A rapid sample-preparation technique for thin-layer chromatographic analysis for 11-Nor-Δ9-tetrahydrocannabinol-9-carboxylic acid in human urine

Abstract

In this rapid TLC method of analysis for the urinary cannabinoid metabolite, 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH), hydrolyzed urine specimens are aspirated through a porous, alkyl-silica extraction layer located along the lower edge of a biphasic thin-layer chromatogram; THC-COOH is simultaneously extracted from the sample and concentrated on the TLC plate for subsequent migration and detection. The method, evaluated in a blind study, identified all samples containing THC-COOH ≥20 μg/L. The technique increases sample throughput, sensitivity, and specificity as compared with conventional TLC methods and is applicable to a wide variety of compounds.