Application of ligand-exchange chromatography to the assay of L-alanine from DL-aspartic acid by Pseudomonas dacunhae.

A direct chiral ligand-exchange chromatographic method was developed to monitor L-alanine production by fermentation. A mobile phase containing aqueous 0.25 mM Zn2+ solution is utilized to separate amino acids in the fermentation medium. The detection limit for L-alanine is 0.5 ppm and the analysis time for one sample is about 8 min. As sample preparation is simple and the matrix effects are minimal, the assay is fast and convenient. The results indicate that the method has potential for the analysis of complicated fermentation media.