title: Chemiluminometric flow-injection method for determination of free l-malate in wine with co-immobilized malate dehydrogenase/NADH oxidase.
abstract: A flow-injection system with a co-immobilized malate dehydrogenase/reduced nicotineamide adenine dinucleotide (NADH) oxidase reactor and a chemiluminometer is described for the determination of free l-malate in wine. Malate dehydrogenase and NADH oxidase were co-immobilized on poly(vinyl alcohol) beads and packed into a stainless-steel column (5 cm x 4 mm i.d.). The hydrogen peroxide produced was detected chemiluminometrically via a luminol-hexacyanoferrate(III) reaction. The calibration graph was linear from 3 x 10(-7) M to 2.5 x 10(-4) M (the linear correlation coefficient was 0.9998); the detection limit (signal-to-noise ratio, 3) was 8 x 10(-8) M. The sample throughput was 30 h(-1) without carryover. The ractor was renewed every 2 weeks.
authors.affiliation: Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Yamanashi University, Kofu 400, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Kiba
authors.forename: J
authors.initials: J
authors.lastname: Inagaki
authors.forename: M
authors.initials: M
authors.lastname: Furusawa