Volume 37 (2016) Issue 1 Pages 23-28
We have developed a high-resolution chiral derivatization-LC method for the determination of D- and L-amino acids using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM) as an enantioseparation enhancer. In this method, D- and L-amino acids were derivatized with (S)-(-)-1-(naphthyl)ethylamine (NEA) in the presence of DMT-MM as a condensing agent. These conditions resulted in the amino group of the D- and L-amino acid-NEA derivative being introduced in the triazine unit of DMT-MM, producing sterically bulky diastereoisomers. The resulting derivatives of the D- and L-amino acids could be discriminated and successfully enantioseparated through reversed-phase LC. This enantioseparation enhancement effect was demonstrated when using six other commercially available chiral amines as derivatization reagents. Since triazine modification possesses high ESI-responsivity, they showed higher sensitivities than non-triazine derivatives. The developed derivatization method was successfully applied to highly sensitive quantification of D- and L-amino acids by combining LC-MS/MS analysis.