Pretreatment of Urine Samples for the Analysis of 11-nor-Δ9-Tetrahydrocannabinol-9-Carboxylic Acid Using Solid-Phase Extraction

Abstract
An extraction and concentration procedure using a unique solid-phase extraction tube was developed for the analysis of 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid in urine. Absolute and relative recoveries of the drug metabolite were found to be greater than 85% and 92%, respectively. The extraction procedure allows quantitation of the drug metabolite by GC/MS, HPLC with UV detection, or GC with flame ionization detection. The extraction procedure was verified with urine samples obtained from marijuana users as well as spiked urine samples.