Cannabinoids in Humans. I. Analysis of  9-Tetrahydrocannabinol and Six Metabolites in Plasma and Urine Using GC-MS

Abstract

This report describes a method for the quantitative analysis of delta 9-tetrahydrocannabinol and six of its metabolites, 8 alpha-hydroxy-delta 9-tetrahydrocannabinol, 8 beta-hydroxy-delta 9-tetrahydrocannabinol, 11-hydroxy-delta 9-tetrahydrocannabinol, 8 alpha,11-dihydroxy-delta 9-tetrahydrocannabinol, 8 beta,11-dihydroxy-delta 9-tetrahydrocannabinol, and 11-nor-9-carboxy-delta 9-tetrahydrocannabinol. In addition, the method was designed to detect cannabidiol and cannabinol, two naturally occurring cannabinoids. Plasma and urine samples were hydrolyzed with bacterial (Escherichia coli) beta-glucuronidase and extracted with hexane-ethyl acetate (7:1). Analysis and quantitation were performed by gas chromatography-mass spectrometry in the electron ionization mode coupled with selected ion monitoring. The cannabinoids were detected as their trimethylsilyl derivatives to enhance their chromatographic separation and mass spectral characteristics. The linearity of the procedure was excellent for all of the compounds within the range tested (0-100 ng/mL). Limits of detection ranged from 0.5 to 1.5 ng/mL in urine and from 0.6 to 2.1 ng/mL in plasma depending on the analyte.

Validated Gas Chromatographic–Negative Ion Chemical Ionization Mass Spectrometric Method for Δ9-Tetrahydrocannabinol in Sweat Patches

“…The flow controller on the mass spectrometer was set to allow 40% methane into the mass spectrometer, with the regulator on the methane tank set to 69 kPa (10 psi). The following ions were monitored: m/z 410 for THC-d 0 , and m/z 413 for THC-d 3 .…”

“…Toxicologic analysis to determine cannabis use includes measurement of THC, the active metabolite 11-hydroxy-tetrahydrocannabinol, and the inactive metabolite 11-nor-9-carboxy-tetrahydrocannabinol. Numerous methods for the analysis of cannabinoids in blood and urine have been developed, primarily using gas chromatography-mass spectrometry (GC/MS) in electron impact ionization (EI) mode (1)(2)(3)(4)(5)(6).…”

Determination of ∆-9-Tetrahydrocannabinol (THC), 11-hydroxy-THC, 11-nor-9-carboxy-THC and Cannabidiol in Human Plasma using Gas Chromatography–Tandem Mass Spectrometry

“…Gas chromatography-mass spectrometry (GC-MS) was initially used to measure THC and metabolites in human plasma (14,(25)(26)(27)(28)(29)(30). More recently 2-dimensional GC-MS has been employed to provide more sensitive analysis of plasma cannabinoids (31,32).…”

“…Because cannabinoid compounds are very lipophilic, extraction procedures are often complicated. Most early GC-MS method extraction procedures required a protein precipitation and/or ß-glucuronidase step was used purportedly to disrupt the binding of cannabinoid compounds to plasma proteins (14,25,26,29). Some utilized lengthy liquid-liquid procedures where either separate extracts were obtained for the neutral cannabinoid compounds (THC and OH-THC) and the acidic COOH-THC (25,26), or multiple extractions after derivatization (28).…”

“…Most early GC-MS method extraction procedures required a protein precipitation and/or ß-glucuronidase step was used purportedly to disrupt the binding of cannabinoid compounds to plasma proteins (14,25,26,29). Some utilized lengthy liquid-liquid procedures where either separate extracts were obtained for the neutral cannabinoid compounds (THC and OH-THC) and the acidic COOH-THC (25,26), or multiple extractions after derivatization (28). More recent GC-MS methods use solid phase extraction (SPE) procedures with (29,31,32), or without (27,28) prior protein binding disruption procedure.…”