Problems of Forensic Sciences 2005 Vol. 62 (LXII) 178-187
DETERMINATION OF TETRAHYDROCANNABINOLS IN SALIVA
Maciej KOCHANOWSKI1,2, Maria KAŁA2
1Faculty of Chemistry, Jagiellonian University, Krakow
2Institute of Forensic Research, Krakow
Streszczenie
A modified and validated method for the extraction and simultaneous determination of Δ9-tetrahydrocannabinol (THC) and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THCCOOH), and detection of 11-hydroxy-Δ9-tetrahydrocannabinol (11-OH-THC) in a single saliva sample using negative ion gas chromatography mass spectrometry (GC-MS-NCI) is presented. Internal standardisation was carried out using deuterated analogues of each analyte. THC and 11-OH-THC were derivatised with tri-fluoroacetic anhydride in chloroform and THCCOOH with pentafluoropropanol in trifluoroacetic anhydride. Quantification was performed using selected ion monitoring mode and the target ions (m/z) were 389.3 and 410.3 for 9THC, 387.3 and 408.3 for 11-OH-THC, and 422.3 and 572.3 for THCCOOH derivatives. Validation parameters for THC and THCCOOH were as follows: limit of detection (LOD) – 0.25 ng/ml, limit of quantification (LOQ) – 0.5 ng/ml and linearity range (LOL) – 0.5–20 ng/ml. Mean recovery rates of THC and THCCOOH from saliva ranged from 50% to 80%, respectively. The intra- and inter-day precision (expressed by RSD) did not exceed 24% for THC and 7% for THCCOOH. The elaborated method was used to determine THC and THCCOOH in 20 paired blood and saliva specimens collected from 12 patients following smoking of marihuana. Saliva and blood were collected at admission to hospital and after 24 h of patient hospitalisation. The concentrations of THC and THCCOOH in blood and THC in saliva varied a lot. At admission to hospital, the mean THC concentration in blood was 8.48 ng/ml (range 0.5–26.4 ng/ml), and after 24 h, this value was 2.73 ng/ml (range: 0.5–15.3 ng/ml). The THC concentrations in saliva were 6.96 (range: 0.5–32.5 ng/ml) and 1.64 ng/ml (range: 0.5–10.4 ng/ml) at the respective sampling points. After 24 hours of patient hospitalisation, the concentrations of THC fell to between 50% (of initial values) and a level under the LOD. The method was also applied to certification of point of collection immunoassay testing devices.
Słowa kluczowe
Δ9-tetrahydrocannabinol; Alternative materials; Determination; GC-MS-NCI.