1989 Volume 38 Issue 11 Pages 622-626
Controlled potential coulometry using electrolyte containing β-D-glucose oxidase, peroxidase and hexacyanoferrate(II) ions was carried out to determine D-glucose selectively. This method has been designated as biocoulometry. D-Glucose added to an electrolyte confined in the pores of porous carbon felt is oxidized by oxygen in the presence of β-D-glucose oxidase, and hydrogen peroxide is produced. Hexacyanoferrate(III) ions produced by the reaction of hydrogen peroxide and hexacyanoferrate(III) ion catalyzed by peroxidase are electrooxidized completely at a -0.5 V vs. counter electrode. The current efficiencies of hydrogen peroxide and D-glucose were found to be nearly 100% and 64%, respectively at pH 5.6 and 22°C. Determination of the time for D-glucose indicated about one minute within 2% of relative standard deviation. This technique was used to determine D-glucose in human, calf and horse sera. The analytical results obtained by coulometry were in fairly good agreement with those by spectrophotmetry. Peroxidase and β-D-glucose oxidases in an electrolytic solution retained their enzyme activity at least for ten days and it was possible to analyze more than 1000 samples using the same electrolyte.
