Confirmation of EMIT cannabinoid assay results by bonded phase adsorption with thin layer chromatography.

Clinical urine specimens were screened for the presence of cannabinoids using the EMIT Cannabinoid Assay. Aliquots of these samples were also analyzed for 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid (THCA), the major cannabis metabolite in urine, by a technique which combines bonded phase adsorption (BPA) and thin layer chromatography (TLC). A 100% agreement between EMIT and BPA-TLC results was observed when at least 20 mL of urine was assayed by BPA-TLC. Bonded phase adsorption coupled with thin layer chromatography appears to be a suitable technique for the confirmation of positive EMIT Cannabinoid Assay results.