Rapid quantification of free and glucuronidated THCCOOH in urine using coated well plates and LC-MS/MS analysis.

Aim: Generally, urine drug testing for cannabis abuse involves measuring total concentrations of 11-nor-9-carboxy-Delta(9)- tetrahydrocannabinol (THCCOOH) obtained by enzymatic and/or alkaline hydrolysis of THCCOOH-glucuronide. As hydrolysis can be inconsistent and incomplete, direct measurement of the two metabolites is preferable. Methodology & results: We developed a high-throughput LC-MS/MS method for simultaneous quantification of free and glucuronidated THCCOOH in urine using coated 96-well plates for analyte extraction and column-switching chromatography. Excellent separation of the two analytes was achieved within 2.5 min, with linear ranges from 5 to 2000 mu g/l for THCCOOH and from 10 to 4000 mu g/l for THCCOOH-glucuronide. Conclusion: The method was successfully validated and applied to authentic urine samples from cannabis consumers, demonstrating its applicability for routine cannabinoid testing.