The rapid emergence of new chiral psychoactive substances makes the simultaneous separation of enantiomers and structural isomers crucial for distinguishing compounds with identical molecular masses but with different pharmacological and toxicological properties, as well as frequently with a different legal status. Enantioselective high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) plays a key role in identifying new chiral psychoactive substances, profiling their distinct pharmacokinetics, and supporting regulatory and forensic efforts. Despite its high sensitivity and accuracy, a mass spectrometer cannot differentiate enantiomers, and a differentiation of positional isomers is often challenging. Therefore, enantiomers and/or positional isomers have to be pre-separated prior to entering the mass spectrometer. This chapter describes the simultaneous separation and enantioseparation of positional isomers of chloromethcathinones (CMCs) and methylmethcathinones (MMCs).