Gas chromatographic-mass spectrometric confirmation of radioimmunoassay results for cannabinoids in blood and urine

Rapid quantification of free and glucuronidated THCCOOH in urine using coated well plates and LC–MS/MS analysis

Aim: Generally, urine drug testing for cannabis abuse involves measuring total concentrations of 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THCCOOH) obtained by enzymatic and/or alkaline hydrolysis of THCCOOH-glucuronide. As hydrolysis can be inconsistent and incomplete, direct measurement of the two metabolites is preferable. Methodology & results: We developed a high-throughput LC–MS/MS method for simultaneous quantification of free and glucuronidated THCCOOH in urine using coated 96-well plates for analyte extraction and column-switching chromatography. Excellent separation of the two analytes was achieved within 2.5 min, with linear ranges from 5 to 2000 μg/l for THCCOOH and from 10 to 4000 μg/l for THCCOOH-glucuronide. Conclusion: The method was successfully validated and applied to authentic urine samples from cannabis consumers, demonstrating its applicability for routine cannabinoid testing.

Gas chromatographic-mass spectrometric methods of analysis for detection of 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid in biological matrices

Gas chromatographic-mass spectrometric methods of analysis for the detection of 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid, a major metabolite of delta 9-tetrahydrocannabinol, are reviewed. Emphasis is on analytical methodology including numerous derivatization techniques developed specifically for this analyte. The majority of procedures cited in the literature were developed to detect this metabolite in the blood and urine of man.

Systematic toxicological analysis of drugs and their metabolites by gas chromatography-mass spectrometry

Gas chromatographic-mass spectrometric (GC-MS) procedures for the systematic toxicological analysis of several categories of drugs relevant to clinical toxicology, forensic toxicology and doping control are reviewed. Papers from 1981 to 1991 are taken into consideration. They describe the detection of acute or chronic intoxication and the detection of drug abuse. Screening procedures are included for the following categories: barbiturates and other sedative-hypnotics, anticonvulsants, benzodiazepines, antidepressants, phenothiazine and butyrophenone neuroleptics, central stimulants (amphetamines, cocaine), hallucinogens (LSD, phencyclidine, tetrahydrocannabinol), opioid (narcotic) and other potent analgesics, non-opioid analgesics, antihistamines (histamine H1-receptor blockers), antiparkinsonian drugs, beta-blockers (beta-adrenoceptor blockers), antiarrhythmics (class I and IV), diuretics, laxatives and their metabolites. Methods for confirmation of results obtained by screening procedures using immunoassay or chromatographic techniques are also included. GC-MS procedures for the simultaneous detection of several categories of drugs, the so-called "general unknown analysis", are reviewed. The toxicological question to be answered and the consequence for the choice of an adequate method, the sample preparation and the chromatography itself are discussed. The basic information about the biosample assayed, work-up, GC column, mass spectral detection mode, reference data and sensitivity of each procedure are summarized in tables, arranged according to the category of drug. Examples of typical GC-MS applications are presented. Fragment ions that are suitable for mass spectral screening for particular categories of drugs and for general unknown are tabulated.

Aberrant radioimmunoassay results for cannabinoids in urine

False negative and false positive radioimmunoassay results for cannabinoids in urine are reported. Such results occur infrequently and appear to be due to non-specific binding of the radiolabel by interfering substances, possibly proteins, in the specimens. False negatives arise when these substances and the non-specifically bound radiolabel are precipitated by polyethylene glycol in the separation stage of the assay, increasing the radioactivity in the bound fraction and thus lowering the assay result. False positives occur when the interfering substances and non-specifically bound radiolabel remain in solution during the separation stage, increasing the radioactivity in the free fraction and giving an erroneously high result. False positives could also occur in assays involving solid-phase antibodies or second-antibody separations. Methanol treatment of the samples prior to analysis precipitates the interfering substances and eliminates the aberrant effect. The interfering substances have not been identified through common serum proteins and semen have been excluded. No common factor in the circumstances of the cases that can account for the results has been identified.