Preparation of AuCo Alloy Particles-Graphene Composite Film Modified Electrode and Its Application in Determination of Sulfite

AuCo particles were electrodeposited on a graphene( GN) coated glassy carbon electrode( GCE)at -1. 0 V( vs. SCE) from 1 mmol / L HAuCl4+ 20 mmol / L Co( NO3)2+ 0. 2 mol / L Na2SO4+ 0. 04 mmol /L sodium dodecyl sulfonate solution. The obtained AuCo particles showed spherical shape with thorns and they were well distributed on the GN surface. The AuCo alloy particles presented catalysis to the electrochemical oxidation of sulfite that could produce a sensitive anodic peak at the resulting AuCo / GN / GCE electrode in H2SO4 solution. Under the optimized conditions the response current of the electrode at 0. 4 V and the sulfite concentration presented linear relationship over the ranges of 0. 5-28 μmol / L and 36-324 μmol / L. The detection limit was 0. 2 μmol / L( S / N = 3). The modified electrode also displayed good stability and reproducibility. When it was applied to the determination of sulfite in drink samples the recovery for standard addition was 94%-109%.