Effective specimen pretreatment and GC-MS protocols were developed for the analysis of 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH) in urine. d3- and d9-11-nor-9-carboxy-Δ9-tetrahydrocannabinol (d3- and d9-THC-COOH) were evaluated as internal standards and conclusions were reached that THC-COOH can be effectively analyzed, qualitatively and quantitatively, as trimethylsilyl derivative using selective ion monitoring of the following ions: m/z 371, 473 and 488 (for THC-COOH) and m/z 380, 479 and 497 (for d9-THC-COOH). The extraction procedure achieved 90% recovery of the analyte in fortified drug-free urine containing 10-200 ng/ml THC-COOH. Using 2-ml sample size, the overall protocol resulted in the following analytical parameters in the 10-200 ng/ml concentration range studied: interday and intraday precision ranges, 0.35-5.31% and 0.44-5.19%, respectively; linearity, r2 > 0.999.
Lin, D.-L.; Kuo, T.-L.I.; and Liu, R.H.
"Gas Chromatography-Mass Spectrometry Analysis of 11-Nor-9-carboxy-Δ9-Tetrahydrocannabinol in Urine,"
Journal of Food and Drug Analysis: Vol. 7
, Article 6.
Available at: https://doi.org/10.38212/2224-6614.2884