Liquid chromatography tandem mass spectrometry determination of selected synthetic cathinones and two piperazines in oral fluid. Cross reactivity study with an on-site immunoassay device

• We developed a LC–MS/MS method for selected synthetic cathinones and piperazines.
• We assessed synthetic cathinones cross reactivity on an on-site screening device.
• The method fulfilled the acceptance criteria for the assessed validation parameters.
• All the analytes cross react with methamphetamine immunoassay at high concentrations.

Since the past few years, several synthetic cathinones and piperazines have been introduced into the drug market to substitute illegal stimulant drugs such as amphetamine and derivatives or cocaine due to their unregulated situation. These emerging drugs are not usually included in routine toxicological analysis. We developed and validated a LC–MS/MS method for the determination of methedrone, methylone, mephedrone, 3,4-methylenedioxypyrovalerone (MDPV), fluoromethcathinone, fluoromethamphetamine, 1-(3-chlorophenyl)piperazine (mCPP) and 3-trifluoromethylphenylpiperazine (TFMPP) in oral fluid. Sample extraction was performed using Strata X cartridges. Chromatographic separation was achieved in 10 min using an Atlantis® T3 column (100 mm × 2.1 mm, 3 μm), and formic acid 0.1% and acetonitrile as mobile phase. The method was satisfactorily validated, including selectivity, linearity (0.2–0.5 to 200 ng/mL), limits of detection (0.025–0.1 ng/mL) and quantification (0.2–0.5 ng/mL), imprecision and accuracy in neat oral fluid (%CV = 0.0–12.7% and 84.8–103.6% of target concentration, respectively) and in oral fluid mixed with Quantisal™ buffer (%CV = 7.2–10.3% and 80.2–106.5% of target concentration, respectively), matrix effect in neat oral fluid (−11.6 to 399.7%) and in oral fluid with Quantisal™ buffer (−69.9 to 131.2%), extraction recovery (87.9–134.3%) and recovery from the Quantisal™ (79.6–107.7%), dilution integrity (75–99% of target concentration) and stability at different conditions (−14.8 to 30.8% loss). In addition, cross reactivity produced by the studied synthetic cathinones in oral fluid using the Dräger DrugTest 5000 was assessed. All the analytes produced a methamphetamine positive result at high concentrations (100 or 10 μg/mL), and fluoromethamphetamine also at low concentration (0.075 μg/mL).