Microscale on-line production and determination of malic acid using flow injection analysis, immobilized fumrase and malate dehydrogenase with chemiluminescence detection

Abstract

Microscale on-line production of l-malic acid from fumaric acid using on-line immobilized fumrase is developed. Fumaric acid is aspirated continuously through immobilized fumarase using a flow injection manifold. A simple and rapid flow injection chemiluminescence system based on an immobilized malate dehydrogenase, methylene blue and luminol system is developed to monitor the production of malic acid. The log-log calibration graph for malate is linear from 4.0×10 −6 to 8.0×10 −5 M. The detection limit (3 σ) is 4.0×10 −6 M. The RSD of 5 replicate injections of 3.2×10 −5 M malate is 3%. The conversion yield of malic acid is 30–95% depending on the concentration of fumaric acid used.