This requires access to mandelic acid, a chemical not watched or controlled as its a fatty acid. The d-isomer acid only dissolves the d out of racemic, leaving l behind and vice Versa w l-mandelic. Chem player on YouTube has a bunch of decent videos on syntheses of watched chems. There's a decent chance other fatty acids could substitute mandelic, but remember like attracts like, which is why methylbenzene (toluene) is good for isolation of meth from pse. I also found its possible to separate meth from pse using hydrogen peroxide (regular Otc kind) to oxidize pse to benzaldehyde (and perhaps but unlikely methcathinone) which is a liquid at room temp, smells like almond extract or cherry flavor and mixes w water. Mn2o3 from alkaline batteries or even rust will catalyze this reaction.