Simultaneous enantioselective determination of 2-, 3-, and 4-methylmethcathinones; their isomers; and major phase-1 metabolites in oral fluid of drug abusers using enantioselective high-performance liquid chromatography-tandem mass spectrometry.

The most powerful and widely used detector for clinical and toxicological analyses is undoubtedly the mass spectrometer (MS) due to its specificity and high sensitivity. However, it cannot differentiate enantiomers from each other, as well as cannot easily distinguish between positional isomers. Therefore, the components of interest to the analysis at hand need to be separated prior to their detection by MS in order to reliably identify and quantify their enantiomers and positional isomers. In the present study, the simultaneous chemo- and enantioseparation of the drugs of abuse, 2-, 3-, and 4-methylmethcathinones, is described. The developed method was applied to 15 oral fluid (OF) samples collected by police in Belgium and found positive for mephedrone (4-methylmethcathinone, 4-MMC) based on a nonselective method for enantiomers and positional isomers. However, re-analyzing these samples with the analytical method proposed in this report indicated that mephedrone was present in only 1 of them, while 6 samples contained 3-methylmethcathinone (3-MMC) and 12 samples contained 2-methylmethcathinone (2-MMC). At the same time, four OF samples contained both 2- and 3-MMC. The developed method enabled the enantioselective analysis of major metabolites of methylmethcathinones, such as their N-demethyl derivatives (nor-MMCs), as well as, at least partially, of their dihydrometabolites. In addition to their positional isomers, other structural isomers of MMCs, such as buphedrone, metamfepramone, and ethcathinone, could also be detected enantioselectively.