Low-potential reduction of sulfite at a ruthenium-oxide hexacyanoferrate modified electrode

The low-potential reduction of sulfite at a ruthenium-oxide hexacyanoferrate (RuOHCF)-modified electrode is reported. A decrease (200 mV) in the overpotential of the sulfite reduction reaction and a substantial current increase (compared to the bare glassy-carbon electrode) were verified. Evidence is found for a mass transport regime which includes a thin-layer diffusional process (sulfite species trapped within the RuOHCF film) responsible for the lowered reductive potential (rather than electrocatalytic properties of the film). The low-potential (− 0.2 V vs. Ag/AgCl/saturated KCl) amperometric detection of sulfite in 0.25 mol L− 1 HCl was free of interferences from substances typically found in food samples.

► Low-potential reduction of sulfite at ruthenium-oxide hexacyanoferrate.
► Decrease in the overpotential of sulfite reduction and ample current increase.
► Contribution from thin-layer diffusional process is evidenced.
► Amperometric detection of sulfite free of interferences from food constituents.