An ultra-high-pressure liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for the detection of cannabinoids in whole blood using solid phase extraction

Abstract

ABSTRACT A novel high-throughput method using automated solid-phase extraction (SPE) coupled with ultra-high-pressure liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) was developed in order to quantify Δ9-tetrahydrocannabinol (THC) and its major metabolites and screen for several synthetic cannabinoids. Cannabinoids and synthetic cannabinoids were extracted from ovine whole blood using Phenomenex Strata-X Drug B SPE columns. Multiple reaction monitoring (MRM) mode was used to monitor at least two transitions of the analyte and its deuterated internal standard. Calibration was fitted quadratically (R2 > 0.995) over a range from 1 to 20 ng/mL for THC, 11-hydroxy-THC, cannabinol and cannabidiol, and 10 to 200 ng/mL for 11-nor-Δ9-carboxy-tetrahydrocannabinol and its glucuronide. Inter-assay accuracy and precision were evaluated over n = 3 analyses spanning six days. With the exception of cannabidiol, the accuracies ranged from 0.52% to 8.63% and the coefficient of variation (%CV) was found to range from 1.91% to 7.69%. Intra-assay accuracy and the precision of these analytes (n = 16) was found to range from 0.16% to 11.42% and from 1.10% to 8.40%, respectively. Cannabidiol intra- and inter-assay accuracy and precision were more variable than for other analytes. The procedure minimized specimen handling, extraction and reduced runtime as compared with an existing gas chromatography–mass spectrometry method and permitted the qualitative identification of several synthetic cannabinoid species.