In the
present paper, the fill and flow channel biosensor concept is
extended to the determination of sulfite, which has the complication
of both the product of the enzyme reaction and the
analyte itself being electroactive at the same potential. Sulfite
oxidase is immobilized in carbon paste with Kel-F oil. One
predictor electrode is located upstream of the enzyme layer to
determine the total oxidation current of sulfite and interfering
species.