ABSTRACT
A new thin-layer chromatographic (TLC) method has been evaluated for the detection of the major urinary marijuana metabolite, ll-nor-A9-tetrahydrocannabinol-9-carboxylic acid (A9-THC-COOH). Using this method, hydrolyzed urine samples are aspirated directly through a small, porous disk composed of bonded silica impregnated within a glass fiber matrix. The THC metabolite is retained by the bonded silica adsorbent through the process of solid-phase extraction. The disk is inserted into a hole in a silica gel/glass fiber TLC plate for subsequent TLC development and detection. Chromatograms were dried on an electric warmer for 3 min after migration. Visualization of A9-THC-COOH was achieved by dipping each chromatogram into a solution of Fast Blue BB salt (0.1% in dichloromethane) and then exposing the chromatogram to diethylamine vapor. Thin-layer chromatograms were preserved by placing transparent tape (Highland, 3M Co.) across both sides of the TLC media at the R/of A9-THC-COOH. When stored protected from light, chromatograms were stable for at least 1 year.
