4-(4,6-Dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride as an enantioseparation enhancer for fluorescence chiral derivatization–liquid chromatographic analysis of dl-lactic acid

• A fluorescence chiral derivatization–LC analysis of DL-lactic acid has been developed.
• We found DMT-MM functions as a separation enhancer for the chiral derivatization.
• Separation enhancement effect of DMT-MM could be applied to seven commercial chiral amines.
• We applied this method to the successful quantification of DL-LAs in foodstuffs.

This paper reports a novel fluorescence chiral derivatization–liquid chromatography (LC) method for the analysis of d- and l-lactic acids (LAs) using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM) as an enantioseparation enhancer. In this method, the dl-LAs were fluorescently derivatized with (S)-(+)-4-(N,N-dimethylaminosulfonyl)-7-(3-aminopyrrolidin-1-yl)-2,1,3-benzoxadiazole [(S)-(+)-DBD-APy] in the presence of DMT-MM as a condensing agent. These conditions resulted in the hydroxyl group of the LA derivative being etherified by the triazine unit of DMT-MM, producing sterically bulky diastereoisomers. The resulting fluorescent diastereoisomers of d- and l-LAs could be discriminated and successfully enantioseparated through reversed-phase LC. The enhancement effect of the derivatization agent DMT-MM when using seven other commercially available chiral amines was also demonstrated. Finally, this method was successfully applied to quantification of dl-LAs in foodstuffs (yogurts and fermented milk drinks).