DETERMINATION OF 2-KETO-L-GULONIC, 2-KETO-D-GLUCONIC AND 2,5-DIKETO-D-GLUCONIC ACIDS BY CAPILLARY ZONE ELECTROPHORESIS

During the biosynthetic processing of 2-keto-L-gulonic acid (2-KLG) fr om 2,5-diketo-D-gluconic acid (2,5-DKG) by Corynebacterium sp., 2-keto -D-gluconic acid (2-KDG) is produced as a byproduct. These organic aci ds have been analyzed by high-performance liquid chromatography (HPLC) on an Aminex HPX-87H column, but the resolution was not good enough f or quantitative analysis. We investigated the quantitation of 2-KLG, 2 -KDG and 2,5-DKG using capillary electrophoresis (CE) and the results were compared with those of HPLC. With CE, in contrast to HPLC, good r esolution, efficiency and rapid analysis were demonstrated as well as low consumption of solvent and samples. The CE system was applied at 1 5 kV with UV detection at 195 nm using 100 mM sodium berate (pH 8.4) a s an electrolyte. The results were shown within 5 min with efficiency approaching 100000 theoretical plates. The relative standard deviation s of migration time and peak area were less than 0.9% and 1.6%, respec tively. The detection limits for quantitative determination were 0.5-1 .3 mu M level. The above compounds, in fermentation broth, were analyz ed under the optimum conditions. Considering the results of our study, the CE method should be highly suitable for the separation of 2-KLG, 2-KDG and 2,5-DKG in the fermentation broth.