Determination of L- and D-amino acids in foodstuffs by coupling of high-performance liquid chromatography with enzyme reactors

A technique is described for the enantiomeric determination bf L- and D-ami no acids. It works on the principle that the separation efficiency of high- performance liquid chromatography is coupled with the specificity of enzyme s and the sensitivity of electrochemical detection. After separation on a l ithium cation-exchange column the amino acids are converted into keto acids and hydrogen peroxide under catalyzation of L- or D-amino acid oxidase. Hy drogen peroxide is detected amperometrically. The method has been tested by the analysis of beer, port, sherry, wine and fruit juice. A main emphasis was put onto the determination of D-alanine which can serve as an indicator for bacterial contamination. It is shown that a coupling o f HPLC with enzyme reactors is a suitable technique for the rapid detection of this marker.