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Quantification of cannabinoids in human hair using a modified derivatization procedure and liquid chromatography–tandem mass spectrometry
Author(s) -
AlZahrani Mansour A.,
AlAsmari Ahmed I.,
AlZahrani Farouq F.,
Torrance Hazel J.,
Watson David G.
Publication year - 2021
Publication title -
drug testing and analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.065
H-Index - 54
eISSN - 1942-7611
pISSN - 1942-7603
DOI - 10.1002/dta.3005
Subject(s) - chemistry , chromatography , cannabinol , derivatization , detection limit , tandem mass spectrometry , solid phase extraction , metabolite , benzoylecgonine , extraction (chemistry) , mass spectrometry , hair analysis , liquid chromatography–mass spectrometry , bstfa , synthetic cannabinoids , cannabinoid , biochemistry , medicine , receptor , alternative medicine , pathology
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.