Temporal indication of marijuana use can be estimated from plasma and urine concentrations of delta9-tetrahydrocannabinol, 11-hydroxy-delta9-tetrahydrocannabinol, and 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid.

Current technology establishes marijuana use based upon detection of the pharmacologically inactive cannabinoid metabolite (11-nor-delta9-carboxy-tetrahydrocannabinol-9-carboxylic acid, THC-COOH) in urine. No accurate prediction of time of use is possible because THC-COOH has a half-life of 6 days. To determine if a temporal relationship between marijuana use and metabolite excretion patterns could be established, eight healthy user-volunteers (18-35 years old) smoked marijuana cigarettes containing 0% (placebo), 1.77%, and 3.58% delta9-tetrahydrocannabinol (THC). Plasma and urine were collected prior to smoking, 5 min after smoking, and hourly thereafter for 8 h for measurement of cannabinoid concentrations by gas chromatography-mass spectrometry. Mathematical models proposed for determination of recent marijuana use were applied to data from this study and verified the temporal use of marijuana. One subject, who later admitted chronic marijuana use (urine baseline THCCOOH, 529.2 ng/mL; plasma, 75.5 ng/mL), excreted 8beta-dihydroxy-THC, peaking 2 h postsmoking (92.3 ng/mL). Urinary THC, the psychoactive component of marijuana, concentrations peaked 2 h after smoking and declined to assay limit of detection (LOD) (1.5 ng/mL) by 6 h. 11-Hydroxy-delta9-tetrahydrocannabinol (11-OH-THC) and THCCOOH were detectable for the entire 8-h testing period but continued to decrease. Urinary concentrations of THC greater than 1.5 ng/mL suggests marijuana use during the previous 8-h time period.

Cannabinoids in humans. I. Analysis of delta 9-tetrahydrocannabinol and six metabolites in plasma and urine using GC-MS.

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.

Cannabinoids in humans. II. The influence of three methods of hydrolysis on the concentration of THC and two metabolites in urine.

Glucuronide conjugates of cannabinoids were previously identified in humans. For gas chromatographic-mass spectrometric (GC-MS) analysis of the unconjugated compounds in human urine, it is necessary to cleave the glucuronide moiety. Base hydrolysis and two forms of enzymatic hydrolysis were compared in this study to examine any quantitative differences between the hydrolysis methods. Human volunteers (n = 8) each smoked one marijuana cigarette containing 3.58% delta 9-tetrahydrocannabinol (THC) and submitted urine samples prior to smoking, 5 min after smoking, and hourly for 8 h thereafter. Urine (1 mL) was buffered to the optimum pH for each form of enzyme tested. beta-Glucuronidase from Escherichia coli (bacteria) or Helix pomatia (mollusk) was added to the specimens, followed by overnight incubation at 37 degrees C. Following hydrolysis, the samples were extracted using hexane-ethyl acetate (7:1) and derivatized with N,O-bis(trimethylsilyl)-trifluoroacetamide plus 1% trimethylchlorosilane, which converted the cannabinoids to their trimethylsilyl derivatives. GC-MS analysis revealed striking differences between the hydrolysis methods. Concentrations of unconjugated THC and 11-hydroxy-THC (11-OH-THC) using E. coli were significantly increased over all other methods tested (p < .05). These results demonstrate the species-dependent nature of glucuronidase activity in hydrolyzing THC and 11-OH-THC glucuronides and the ineffectiveness of base hydrolysis on these hydroxylated compounds. The need for further study to find the optimum conditions necessary for the complete hydrolysis of cannabinoid conjugates is suggested.

Solid-phase extraction and GC/MS quantitation of cocaine, ecgonine methyl ester, benzoylecgonine, and cocaethylene from meconium, whole blood, and plasma.

A selective solid-phase extraction technique has been applied to the analysis of cocaine and selected cocaine metabolites in meconium, whole blood, and plasma. This technique uses a mixed-mode Bond Elut Certify column that utilizes the characteristics of hydrophobic and polar interactions and ion exchange chromatography. Following extraction, cocaine, ecgonine methyl ester, benzoylecgonine, and cocaethylene were identified and quantitated using GC/MS. Linear quantitative response curves have been generated for the metabolites over a concentration range of 0-1000 ng/g for meconium and 0-1000 ng/mL for whole blood and plasma. The overall extraction efficiencies, depending on the metabolite, were between 58.1 and 99.7% for meconium, 95.6 and 124.0% for blood, and 86.9 and 128.9% for plasma. Linear regression analyses of the standard curve for the four analytes exhibited correlation coefficients ranging from 0.850 to 0.946 for meconium, 0.939 to 0.993 for whole blood, and 0.981 to 0.996 for plasma. Because of its capability to detect cocaethylene in meconium, blood, and plasma, the procedure can be used to determine if drug exposure occurred during the latter stages of gestation and if it involved only cocaine or a combination of cocaine and ethanol.