Quantification of cannabinoids in human hair using a modified derivatization procedure and liquid chromatography–tandem mass spectrometry. Issue 6 (16th February 2021)

• Record Type: Journal Article
• Authors: Al‐Zahrani, Mansour A.; Al‐Asmari, Ahmed I.; Al‐Zahrani, Farouq F.; Torrance, Hazel J.; Watson, David G.
• Is Part Of: Drug testing and analysis. Volume 13:Issue 6(2021)
• Page Start: 1095
• Page End: 1107
• Publication Date: 2021-02-16
• Subjects: cannabinoids -- forensic toxicology -- hair -- LC–MS/MS; Drugs -- Analysis -- Periodicals; Drug testing -- Periodicals; Chemistry, Forensic -- Periodicals; 615.1901
• DOI: 10.1002/dta.3005
• Languages: English
• ISSNs: 1942-7603

Abstract

Abstract: The aim of this work was to develop and validate a liquid chromatography–tandem mass spectrometry method for detecting of the main cannabinoids, cannabinol (CBN) and tetrahydrocannabinol (THC) and the primary metabolite 11‐nor‐9‐carboxy‐Δ 9 ‐tetrahydrocannabinol (THC‐COOH) in hair samples. Extraction of the cannabinoids was carried out by a polymeric strong anion mixed‐mode solid‐phase extraction cartridge and then employing methanolic HCl followed by 2‐fluoro‐1‐methylpyridinium‐ p ‐toluenesulfonate (FMP‐TS) as a derivatization procedure of carboxyl and phenolic groups, respectively, offering enhanced sensitivity for the detection of THC‐COOH in hair matrices. Formation of a methyl ester increased its lipophilicity and removed the negative charge on the carboxyl group. Calibration curves were prepared over the range of 0.02–4 pg/mg of hair for THC and CBN and 0.2–12 pg/mg of hair for THC‐COOH. The extraction recovery was between 81% and 105% for all compounds. The limit of detection (LOD) and limit of quantification (LOQ) were 2 and 20 pg/mg, respectively, for both CBN and THC and 0.1 and 0.2 pg/mg, respectively, for THC‐COOH, which met the society of hair testing recommendation. Intra‐assay and interassay precision were always lower than 4% and 11%, respectively for these cannabinoids, whereas intra‐assay and interassay bias were between +14% and −18% and +15% and −12%, respectively. Twenty‐seven hair specimens from cannabis users were investigated. The concentrations of CBN, THC and THC‐COOH gave ranges of (0.022–2.562 ng/mg), (0.049–0.431 ng/mg) and (0.222–4.867 pg/mg), respectively. This new method of derivatization improves the LOD to ensure detection of the metabolite. Abstract : The detection of THC‐COOH in hair matrices requires superior sensitivity due to its extremely low concentrations in a hair sample. In this study, employing 2‐fluoro‐1‐methylpyridinium‐ p ‐toluenesulfonate and methyl esterification as a new derivatization procedure of hydroxyl and carboxyl groups offered enhanced specificity and ionization for the detection of THC‐COOH in human hair matrices.