Confirmation testing of 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid in urine with micellar electrokinetic capillary chromatography.

The major urinary metabolite of the most commonly abused psychotropic drug, delta-9-tetrahydrocannabinol, is 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH). With basic hydrolysis, extraction and concentration, this compound can easily be determined using micellar electrokinetic capillary chromatography with on-column multi-wavelength detection. After solid-phase extraction of 5 ml of urine, drug concentrations down to about 10 ng/ml can be unambiguously monitored. Peak assignment is achieved through comparison of the retention time and absorption spectrum of the eluting THC-COOH peak with those of computer-stored model runs. The effectiveness of the approach is demonstrated with data obtained from urine samples from different patients which tested positively for cannabinoids using a fluorescence polarization immunoassay.