The period of administrative detention of driving license when driving under the influence of drugs is set to 72 hours in France. The respect of that period forced us to develop an assay technique reliable, fast and robust assay of THC and its derivatives (OH-THC and THC-COOH).

Our method consists of an aliquot of 100 μL of whole blood + IS precipitate on Ostro™ 96 Wells (Waters, St Quentin en Yvelines). 50 μL of the eluate were injected onto an HPLC MS/MS Waters Xevo TQD system. Mobile phases consist on the one hand of mixture water + 0.1 % formic acid and on the other hand of acetonitrile + 0.1 % formic acid. Extraction on-line SPE cartridge is a Direct connect and C8 analytical column is a UPLC BEH C18 2.1x100mm 1.7 μm. The analysis lasts 6 minutes.

We get a range of 0.5 to 50ng/mL for 3 composed. The detection limit is 0.1ng/mL for THC and THC-COOH, 0.25ng/mL for THC-OH. On lowest whole blood controls (THC 0.68ng/mL THC-OH 1.01ng/mL THC-COOH and 4.96ng/mL) the repeatability and reproducibility have a CV <15%, on high whole blood controls (17.77ng THC, THC-OH 9.28ng/ml and THC-COOH 65.56ng/mL) they are below 10 %.

We have developed for a rapid (1:30 preparation to reading) and robust (no need for calibration of each series) technique in order to respect the period of administrative detention by allowing us to make sets of cannabis daily.