title: Analysis of Delta9-tetrahydrocannabinol in oral fluid samples using solid-phase extraction and high-performance liquid chromatography-electrospray ionization mass spectrometry.
abstract: An analytical method using solid-phase extraction (SPE) and high-performance liquid chromatography-mass spectrometry (LC-MS) has been developed and validated for the confirmation of Delta(9)-tetrahydrocannabinol (THC) in oral fluid samples. Oral fluid was extracted using Bond Elut LRC-Certify solid-phase extraction columns (10 cm(3), 300 mg) and elution performed with n-hexane/ethyl acetate. Quantitation made use of the selected ion-recording mode (SIR) using the most abundant characteristic ion [THC+H(+)], m/z 315.31 and the fragment ion, m/z 193.13 for confirmation, and m/z 318.00 for the protonated internal standard, [d(3)-THC+H(+)]. The method proved to be precise for THC, in terms of both intra-day and inter-day analyses, with coefficients of variation less than 10%, and the calculated extraction efficiencies for THC ranged from 76 to 83%. Calibration standards spiked with THC between 2 and 100 ng/mL showed a linear relationship (r(2)=0.999). The method presented was applied to the oral fluid samples taken from the volunteers during the largest music event in Portugal, named Rock in Rio-Lisboa. Oral fluid was collected from 40 persons by expectoration and with Salivette. In 55% of the samples obtained by expectorating, THC was detected with concentration ranges from 1033 to 6552 ng/mL and in 45% of cases THC was detected at concentrations between 51 and 937 ng/mL. However, using Salivette collection, 26 of the 40 cases had an undetectable THC.
authors.affiliation: Delegation of Coimbra, National Institute of Legal Medicine, Largo da Sé Nova, 3000-213 Coimbra, Portugal. helena.teixeira@dcinml.mj.pt
authors.forename: Helena
authors.initials: H
authors.lastname: Teixeira
authors.forename: Paula
authors.initials: P
authors.lastname: Proença
authors.forename: Alain
authors.initials: A
authors.lastname: Verstraete
authors.forename: Francisco
authors.initials: F
authors.lastname: Corte-Real
authors.forename: Duarte Nuno
authors.initials: DN
authors.lastname: Vieira
mesh_terms: D000293:Adolescent; D000328:Adult; D002851:Chromatography, High Pressure Liquid; D013759:Dronabinol / Q000032:analysis*; D005260:Female; D005554:Forensic Medicine / Q000379:methods; D006213:Hallucinogens / Q000032:analysis*; D006801:Humans; D008297:Male; D012463:Saliva / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D015813:Substance Abuse Detection / Q000379:methods*
chemical_list: D006213:Hallucinogens; D013759:Dronabinol