SOFT 2004 Meeting Abstracts - Society of Forensic Toxicologists

M31
DETERMINATION OF A'.TETRAHYDROCANNABINOL (THC) IN ORAL FLUID USING
SOLID PHASE EXTRACTION AND HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY
AND ELECTROSPRA Y IONIZATION MASS SPECTROMETRY
H.M. Teixeira *, P. Proenyal, A. Castanheira l , M. L6pez-Rivadulla 2 , F. Corte-Reali, E.P. Marques l , D.N.
'
Vieira l : I National Institute of Legal Medicine, Coimbra, Portugal and 2 Legal Medicine Institute, Santiago
de Compostela, Spain
Aim: High-performance liquid chromatography with electro spray ionization mass spectrometry was used to
determine /19-tetrahydrocannabinol (t/-THe) in oral fluid.
Methods: Oral fluid samples were extracted using Bond Elut LRC-CertiiY solid-phase extraction columns
(lOcc, 300mg), elution performed with n-hexane/ethyl acetate. The separation and quantitation was done on
a positive ion electro spray (ESl positive) high performance liquid chromatography-mass spectrometry (LC­
MS) in the single ion recording (SIR) mode. Quantitation was achieved by the addition of the deuterated
analogue as internal standard. The compounds were detected by single ion monitoring ofmlz 315 and mlz
318 for the protonated molecules [THC+H+J and [d 3 -THC+H+J, respectively. In the chromatographic
separation, a X-Terra MS CIS column (2.1x50mm, 3.5j.1m) was used and the mobile phase was
composed of acetonitrile and ammonia 0.05%, at a OJ mLimin flow rate.
Results: No interferences were detected in 10 blank oral fluid samples of different origin. The precision and
accuracy were tested on spiked oral fluid samples at three different concentrations (2, 25 and 100nglmL).
The mean recovery was 79%, coefficients of variations were between 2.9-6.9% and the limits of detection
(LOD) and quantitation (LOQ) were 1.0 nglmL and 2.0 ng/mL, respectively. Calibration curves for /e/.
THC were performed in methanol solutions and in oral fluid samples using seven different concentrations,
achieving linearity between 2 nglmL and 100 ng/mL. This validated method is currently being applied to
real cases where oral fluid specimens are collected with the Salivette® and also by spitting from marijuana
smokers attending the world's largest music event in recent years, "Rock in Rio - Lisboa".
Conclusions: The method is sensitive, accurate and reproducible and may be utilized in ongoing controlled
cannabinoid administration studies and in roadside studies and thus, important for the fields of forensic
toxicology.
Keywords: /1'-THC, Oral Fluid, LC-MS
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