Fast confirmation of 11-nor-9-carboxy-Delta(9)-tetrahydrocannabinol (THC-COOH) in urine by LC/MS/MS using negative atmospheric-pressure chemical ionisation (APCI).
A fast method using automated solid-phase extraction (SPE) and short-column liquid-chromatography coupled to tandem mass-spectrometry (LC/MS/MS) with negative atmospheric-pressure chemical ionisation (APCI) has been developed for the confirmation of 11-nor-9-carboxy-Delta(9)-tetrahydrocannabinol (THC-COOH) in urine samples. This highly specific method which combines chromatographic separation and MS/MS-analysis can be used for the confirmation of positive immunoassay results with a NIDA cut-off of 15ng/ml. The conjugates of THC-COOH were hydrolysed prior to SPE, and a standard SPE was performed using C18-SPE columns. No derivatisation of the extracts was needed as in GC/MS analysis, and the LC run-time was 6.5min by gradient elution with a retention time of 2.4min. Linearity of calibration was obtained in the range between 0 and 500ng/ml (correlation coefficient R(2)=0.998). Using linear regression (0-50ng/ml) the limit of detection (LOD) was 2.0ng/ml and the limit of quantitation (LOQ) was 5.1ng/ml; day-to-day reproducibility and precision were tested at 15 and 250ng/ml and were 13.4ng/ml+/-3.3% and 255.8ng/ml+/-4.5%, respectively.
Weinmann
W
W
Institute of Legal Medicine, Klinikum der Albert-Ludwigs-Universität Freiburg i. Br., Albertstrasse 9, D-79104 Freiburg, Germany. weinmann@sun11.ukl.uni-freiburg.de
Goerner
M
M
Vogt
S
S
Goerke
R
R
Pollak
S
S
D002853:Chromatography, Liquid / Q000379:methods*; D013759:Dronabinol / Q000031:analogs & derivatives / Q000652:urine*; D006801:Humans; D016014:Linear Models; D013058:Mass Spectrometry / Q000379:methods*
D013759:Dronabinol; C025351:delta(9)-tetrahydrocannabinolic acid