title: Validated method for the simultaneous determination of Delta9-THC and Delta9-THC-COOH in oral fluid, urine and whole blood using solid-phase extraction and liquid chromatography-mass spectrometry with electrospray ionization.
abstract: A fully validated, sensitive and specific method for the extraction and quantification of Delta(9)-tetrahydrocannabinol (THC) and 11-nor-9-carboxy-Delta(9)-THC (THC-COOH) and for the detection of 11-hydroxy-Delta(9)-THC (11-OH THC) in oral fluid, urine and whole blood is presented. Solid-phase extraction and liquid chromatography-mass spectrometry (LC-MS) technique were used, with electrospray ionization. Three ions were monitored for THC and THC-COOH and two for 11-OH THC. The compounds were quantified by selected ion recording of m/z 315.31, 329.18 and 343.16 for THC, 11-OH THC and THC-COOH, respectively, and m/z 318.27 and 346.26 for the deuterated internal standards, THC-d(3) and THC-COOH-d(3), respectively. The method proved to be precise for THC and THC-COOH both in terms of intra-day and inter-day analysis, with intra-day coefficients of variation (CV) less than 6.3, 6.6 and 6.5% for THC in saliva, urine and blood, respectively, and 6.8 and 7.7% for THC-COOH in urine and blood, respectively. Day-to-day CVs were less than 3.5, 4.9 and 11.3% for THC in saliva, urine and blood, respectively, and 6.2 and 6.4% for THC-COOH in urine and blood, respectively. Limits of detection (LOD) were 2 ng/mL for THC in oral fluid and 0.5 ng/mL for THC and THC-COOH and 20 ng/mL for 11-OH THC, in urine and blood. Calibration curves showed a linear relationship for THC and THC-COOH in all samples (r(2)>0.999) within the range investigated. The procedure presented here has high specificity, selectivity and sensitivity. It can be regarded as an alternative method to GC-MS for the confirmation of positive immunoassay test results, and can be used as a suitable analytical tool for the quantification of THC and THC-COOH in oral fluid, urine and/or blood samples.
authors.affiliation: Delegation of Coimbra, National Institute of Legal Medicine, Coimbra, Portugal. helenateixeira@dcinml.mj.pt
authors.forename: Helena
authors.initials: H
authors.lastname: Teixeira
authors.forename: Alain
authors.initials: A
authors.lastname: Verstraete
authors.forename: Paula
authors.initials: P
authors.lastname: Proença
authors.forename: Francisco
authors.initials: F
authors.lastname: Corte-Real
authors.forename: Paula
authors.initials: P
authors.lastname: Monsanto
authors.forename: Duarte Nuno
authors.initials: DN
authors.lastname: Vieira
mesh_terms: D013759:Dronabinol / Q000031:analogs & derivatives* / Q000032:analysis*; D053593:Forensic Toxicology; D008401:Gas Chromatography-Mass Spectrometry; D006213:Hallucinogens / Q000032:analysis*; D006801:Humans; D016014:Linear Models; D012463:Saliva / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D015813:Substance Abuse Detection / Q000379:methods
chemical_list: D006213:Hallucinogens; D013759:Dronabinol; C025351:delta(9)-tetrahydrocannabinolic acid