Development and validation of a liquid chromatography tandem massspectrometry method for the determination of cannabinoids andphase I and II metabolites in meconium

Abstract

tA liquid chromatography–tandem mass spectrometry (LC–MSMS) method was developed and fullyvalidated for the determination of 9-tetrahydrocannabinol (THC), 11-hydroxyTHC (OHTHC), 11-nor-9-carboxyTHC (THCCOOH), 8- -11-dihydroxyTHC (diOHTHC), cannabinol, cannabidiol, and THC andTHCCOOH glucuronides in 0.25 ± 0.02 g meconium. Samples were homogenized in methanol and sub-jected to cation exchange solid-phase extraction. Chromatographic separation was performed on aKinetex C18 column (50 mm × 2.1 mm, 2.6 m) at 35◦C, with a gradient of 0.1% formic acid in waterand acetonitrile at a flow rate of 0.3 mL/min; total run time was 10 min. Two transitions per analyte weremonitored in MRM mode. The method was specific and sensitive; LOD was from 1 to 2 ng/g, and LOQfrom 4 to 10 ng/g; linearity ranged from 4 to 400 ng/g for all the analytes, except for THC glucuronide(10–400 ng/g); intra-assay, inter-assay and total imprecision were <11.2%, <13.45% and <15.6%, respec-tively; accuracy ranged from 93.9% to 109.0% of the target concentration; matrix effect, extraction andprocess efficiency ranged from −26.4% to −71.4%, 49.9% to 69.5% and 14.3% to 45.0%, respectively. Theinclusion of THC and THCCOOH glucuronides avoided the need for the hydrolysis process, thus facilitatingsample pretreatment. Application of the method to 19 authentic meconium specimens from uncontrolledpregnancies or women suspicious of drug consumption revealed fetal cannabis exposure in 4 newborns.THCCOOH (24.1–288.8 ng/g), diOHTHC (53.2–332.4 ng/g), THC (4.2–7.7 ng/g), CBN (30.7–93.3 ng/g) andCBD (7.1–251.5 ng/g) were detected in all cases; THCCOOH glucuronide (190.2–306.8 ng/g) in 3 cases; andOHTHC (11.9 ng/g) in the remaining one; however, THC glucuronide was not identified in any specimen.