Lactic acid enantiomers: separation by thin-layer chromatography on silica gel plates impregnated with Cu2+

A simple and fast method for the separation of D- and L-lactic acid enantiomers by thin-layer chromatographic silica gel precoated plates impregnated with Cu(II) is proposed. The two lactic acid enantiomers, dissolved in acetone, are deposed on these plates. D- and L-lactic acids form complexes with Cu(II), with different Rf values, suitable for radiochemical measurements. The real separation was confirmed by enzymatic tests carried out on spots of D and L forms scraped from the chromatographic plates. Total radioactivity of 14C-labeled D- and L-lactic acids was recovered. A Cu/lactic acid complex is evidenced.