Is the use of tandem mass spectrometry to determine 0.5 µg/L of Δ9-tetrahydrocannabinol in whole blood really necessary?

Olivier Roussel, Sandrine Sabini, Sophie Salle, Damien Coste, Michelle Carlin

Research output: Contribution to conferencePosterpeer-review

Abstract

Aims: Since the decree of September 5th 2001, French toxicologists have had to confirm drug screening in drivers by gas-chromatography (GC) and mass-spectrometry (MS). Furthermore, the French Society of Analytical Toxicology (SFTA) has advocated the determination of Δ9-tetrahydrocannabinol (THC) at 0.5 µg/L in whole blood, since its Cannabis Consensus past on June 13th, 2013. Because of this new analytical target, we had to develop a new method. Our first choice was to use our GC/tandem-MS however we decided to analyse the samples on this instrument alongside our GC/single quadrupole-MS, and validated on both without difficulties. Methods: The extraction method consisted of those from the SFTA’s recommendations with some modifications: a smaller blood volume, another derivatisation reagent. The calibration was composed of a blank blood sample and six blood samples, spiked with cannabinoid standards from 0.3 to 100 µg/L (THC and its two main metabolites). Extracts were analysed with a SHIMADZU QP-2010SE GC-single quadrupole-MS equipped with J&W Ultra 1 column (12 m x 0.20 mm x 0.33 μm) after splitless injection and in SIM mode. Validation was performed with ARLENDA ENOVAL software. Results: For THC, the lower limit of quantification (LLQ) was 0.5 µg/L and the detection limits were 0.2 µg/L, with the ion pair 386/389 m/z. Conclusion: Determining the most appropriate method parameters were the key to this success. Using a calibrator lower than LLQ can be considered as unusual but without it, mathematical model and LLQ were of a lower quality. After this validation, we decided to establish the method as a routine method. After one year of using this method, the Shewhart chart for THC is still good. This method is robust, satisfies the requirements (for THC metabolites too) and costs less. This finding allows us to focus our most sensitive equipment on more demanding analyses.
Original languageEnglish
Publication statusPublished - 2014
Event52nd Annual Meeting of the The International Association of Forensic Toxicologists (TIAFT) - Buenos Aires, Argentina
Duration: 1 Jan 2014 → …
http://www.tiaft2014.com.ar/

Conference

Conference52nd Annual Meeting of the The International Association of Forensic Toxicologists (TIAFT)
Period1/01/14 → …
Internet address

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