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

Abstract

BackgroundCannabis 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. MethodsA 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 0.5ml human urine via supported-liquid extraction. Chromatography was performed on an Ultra Biphenyl column with a gradient of 10mmol/l ammonium acetate, pH 6.15 and 15% methanol in acetonitrile at 0.4ml/min. Analytes were monitored by positive and negative mode electrospray ionization and multiple reaction monitoring mass spectrometry. ResultsLinear ranges were 0.5–50ng/ml for THC-glucuronide, 1–100ng/ml for THCCOOH, 11-OH-THC and cannabidiol, 2–100ng/ml for THC and cannabinol, and 5–500ng/ml for THCCOOH-glucuronide (R2>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. ConclusionThis 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.