No abstract

The study of 34,561 urine specimens, submitted for designer stimulant testing between February 2011 and January 2013, provided an opportunity: to estimate the range of synthetic cathinones (SC) abused in the USA, to observe multiple examples of metabolic profiles for each drug in various stages of excretion in human urine, to evaluate the extent of metabolism of specific SC and to select metabolites or parent drugs for routine testing. Sixteen SC were found in random patient samples: buphedrone; butylone; 3,4-dimethylmethcathinone; ethcathinone; N-ethylbuphedrone; ethylone; flephedrone; mephedrone; 4-methylbuphedrone; 3,4-methylenedioxypyrovalerone (MDPV); 4-methyl-N-ethylcathinone; methylone; pentedrone; pentylone; α-pyrrolidinobutiophenone (PBP) and α-pyrrolidinopentiophenone (PVP). After liquid/liquid extraction and trifluoroacetylation, specimens were screened by gas chromatography-mass spectrometry (GC-MS) for drugs and metabolites excreted free in urine. Each SC exhibited a characteristic metabolic profile, as shown by multiple examples. Metabolites' structures were postulated on the basis of their mass spectra. A large group of SC appears to metabolize extensively by carbonyl reduction into respective substituted ephedrines and further by N-dealkylation into norephedrines. Abundant metabolites in this group are essential markers of the parent drug use. Unchanged drugs are far less abundant or not found at all. SC with methylenedioxy attachment to the aromatic ring, metabolize by carbonyl reduction to a much lesser extent and are best detected as such in free urine fraction. PBP and PVP can be detected either unchanged or as metabolites, resulting from pyrrolidine ring degradation into primary amine followed by carbonyl reduction. MDPV appears in urine as such with no apparent free metabolites.

The determination of the marijuana metabolite 11-nor-Delta(9)-tetrahydrocannabinol-9-carboxylic acid (THCA) in oral fluid specimens is described for the first time using a Quantisal oral fluid collection device and gas chromatography with single-quadrupole mass spectrometric detection. Oral fluid specimens were confirmed for the presence of THCA using two-dimensional gas chromatography-mass spectrometry in order to achieve the low concentration levels previously reported to be present in oral fluid. The extraction efficiency for THCA from the oral fluid collection pad was determined to be 80% at a concentration of 10 pg/mL with a coefficient of variation of 8.23%. The intraday precision of the assay ranged from 3.4% to 7.9% over four concentrations; the interday precision ranged from 8.3% to 18.5%. The limit of quantitation was 2 pg/mL. The method was applied to oral fluid specimens collected from a frequent user of marijuana. Samples were collected almost immediately after the subject smoked and then at intervals of 15 and 45 min and 1, 2, and 8 h after smoking. THCA was present in all the specimens, even the initial specimen taken almost immediately after smoking. The presence of THCA minimizes the argument for passive exposure to marijuana in drug-testing cases.

The presence of the conjugated marijuana metabolite 11-nor-Delta(9)-tetrahydrocannabinol-9-carboxylic acid (THCA) glucuronide in oral fluid specimens is described for the first time. Oral fluid specimens were collected using a Quantisal device and analyzed for the presence of THCA using two-dimensional gas chromatography with mass spectrometric (GC-MS) detection both before and after hydrolysis. The nature of the conjugation was determined by analyzing specimens from a marijuana user without hydrolysis, with base hydrolysis, with beta-glucuronidase treatment, and hydrolysis using sulfatase only. Treatment with sodium hydroxide proved to be the most efficient hydrolytic procedure. Specimens collected over 48 h showed an average conjugation of over 64.5%. The specimens were also analyzed for the active component, tetrahydrocannabinol (THC), which was detected in the oral fluid, in most cases, for up to 24 h. Parent THC was not found to be glucuronide bound. Specimens were then subjected to commercially available immunoassays in order to determine their utility as screening procedures. The metabolite, THCA, was detected in all samples up to and including the specimen 48 h after smoking, using the more sensitive screening assay and two-dimensional GC-MS. Moreover, proof that the THCA is conjugated in oral fluid minimizes concerns associated with passive inhalation.

The proposed federal regulations for the detection in hair of 11-nor-Delta(9)-tetrahydrocannabinol-9-carboxylic acid (THC-COOH), a metabolite of marijuana, require a confirmatory detection level of 0.05 pg/mg. At present, the only way to achieve this on a routine basis has been with the use gas chromatography with tandem mass spectrometry (GC-MS-MS) technology. Tandem MS is an expensive approach and dissuades laboratories from attempting to enter the hair-testing market. A procedure for the determination of THC-COOH in hair using two-dimensional gas chromatography (GC x GC) coupled to mass spectrometry (GC-GC-MS) is described for the first time. The method makes use of several small improvements in the extraction, GC, and MS procedures to allow the required sensitivity to be achieved. The results of this approach demonstrate detection of THC-COOH in hair at a concentration level of 0.05 pg/mg with both a target quantitation ion and a unique confirming qualifier ion, using a single-quadrupole mass selective detector. These two ions and the enhanced separation of the GC-GC provide a high degree of confidence in the determinations. The method has been successfully applied to the detection of THC-COOH in hair specimens from known marijuana users, and it reaches the levels currently proposed in the Federal Register.