C. Cheng, S. C. Wu
Oct 27, 2000
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Influential Citations
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Journal
Journal of chromatography. A
Abstract
D-Aspartic acid can be enzymatically biotransformed with D-amino acid oxidase and aminotransferase to L-aspartic acid. The reaction was surveyed at three temperatures and a period of 3 days, however, L-aspartic acid can be produced only at the reaction temperature 90 degrees C. However, the separation of D-aspartic acid and L-aspartic acid by ligand-exchange chromatography showed matrix interference. Therefore, the column-switching technique by coupling a solid-phase extraction (SPE) column to the analytical ligand-exchange HPLC column was used to eliminate the matrix effect. The pretreatment of reaction samples with the SPE column was considered as a combination of size-exclusion chromatography and ion-pair chromatography. The ion-pair reagent was 0.005 M sodium 1-octanesulfonate aqueous solution adjusted to pH 2.2. Part of the first eluted peak from the SPE column was then switched through the ligand-exchange column and analyzed with a 0.25 mM Cu2+ aqueous mobile phase of pH 3.6. The quantitative analysis of D- and L-aspartic acids was performed by the standard addition method. Overall, the separation and analysis of D- and L-aspartic acids in the enzymic solution was convenient, fast, and successful with the developed on-line LC-LC column-coupling and column-switching system.