Simultaneous quantification of free and glucuronidated cannabinoids in human urine by liquid chromatography tandem mass spectrometry.

BACKGROUND: Cannabis is the most commonly abused drug of abuse and is commonly quantified during urine drug testing. We are conducting a controlled drug administration study investigating efficacy of urinary cannabinoid glucuronide metabolites for documenting recency of cannabis intake and for determining stability of urinary cannabinoids.
METHODS: A liquid chromatography tandem mass spectrometry method was developed and validated quantifying Δ9-tetrahydrocannabinol (THC), 11-hydroxy-THC (11-OH-THC), 11-nor-9-carboxy-THC (THCCOOH), cannabidiol, cannabinol, THC-glucuronide and THCCOOH-glucuronide in 0.5 ml human urine via supported-liquid extraction. Chromatography was performed on an Ultra Biphenyl column with a gradient of 10 mmol/l ammonium acetate, pH 6.15 and 15% methanol in acetonitrile at 0.4 ml/min. Analytes were monitored by positive and negative mode electrospray ionization and multiple reaction monitoring mass spectrometry.
RESULTS: Linear ranges were 0.5-50 ng/ml for THC-glucuronide, 1-100 ng/ml for THCCOOH, 11-OH-THC and cannabidiol, 2-100 ng/ml for THC and cannabinol, and 5-500 ng/ml for THCCOOH-glucuronide (R(2)>0.99). Mean extraction efficiencies were 34-73% with analytical recovery (bias) 80.5-118.0% and total imprecision 3.0-10.2% coefficient of variation.
CONCLUSION: This method simultaneously quantifies urinary cannabinoids and phase II glucuronide metabolites, and enables evaluation of urinary cannabinoid glucuronides for documenting recency of cannabis intake and cannabinoid stability. The assay is applicable for routine urine cannabinoid testing. Published by Elsevier B.V.