A new LC-MS/MS confirmation method for the determination of 17 drugs of abuse in oral fluid and its application to real samples

A new liquid chromatography–tandem mass spectrometry (LC-MS/MS) confirmation method for the direct analysis of 17 drugs starting from 200 µL of diluted oral fluid (OF), in a single chromatographic run, was developed and validated. Cocaine, benzoylecgonine (BEG), cocaethylene, Δ-9-tetrahydrocannabinol (Δ-9-THC), buprenorphine, 6-monoacetylmorphine (6 MAM), morphine, codeine, methadone, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), amphetamine, methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA), methylenedioxyamphetamine (MDA), 3,4-Methylenedioxy-N-ethylamphetamine (MDE), ketamine, N-methyl-1-(1,3-benzodioxol-5-yl)-2-butanamine (MBDB) were determined in a chromatographic run of 12 minutes only with no sample pre-treatment, after the addition of 15 different internal standards (ISs). The method met all requirements in terms of linearity, accuracy (precision and trueness), recovery, and stability requested by FDA guidelines. Carry-over and interferences were negligible, as well as the matrix effects. LLOQs are below the limits defined by European guidelines and Italian national laws. Samples are stable at least six month at -20°C and one week at +4°C