Renewable-surface sol-gel derived carbon ceramic electrode fabricated by [Ru(bpy)(tpy)Cl]PF_6 and its application as an amperometric sensor for sulfide and sulfur oxoanions

摘要

A highly sensitive and fast responding sensor for the determination of thiosulfate, sulfite, sulfite and dithionite is described. It consists of a chemically modified carbon ceramic composite electrode (CCE) containing [Ru(bpy)(tpy)Cl]PF_6 complex that was constructed by the sol-geltecnique. A reversible redox couple of Ru(II)/Ru(III) was observed as a solute in acetonitirle solution and as a component of carbon based conducting composite electrode. Electrochemical behavior and stability of modified CCE were investigated by cyclic voltametry, the apparent electron transfer rate constant (#kappa#_s) and transfer coefficient (#alpha#) were determined by cyclic voltametry which were about 28 s~(-1) and 0.43 respectively. Electrocatalytic oxidation of S~(2-), SO_3~(2-), S_2O_4~(2-) and S_2O_3~(2-) were effective at the modified electrode at significantly reduced over potentials and in the pH range 1-11. Optimum pH values for amperometric detection of thiosulfate, dithionite, sulfide and sulfite are 7, 9, 2 and 2. Under the optimized conditions the calibration curves are linear in the concentration ranges 1-500, 3-80, 2-90 and 1-100 #mu#M for S_2O_3~(2-), SO_3~(2-), S~(2-) and S_2O_4~(2-) determination. the detection limit (signal to noise is 3) ad sensitivity are 05 and 12, 2.8 and 6, 1.6 and 8, and 0.65 #mu#M and 80 nA #mu#M~(-1) for thiosulfate, sulfite, sulfide and dithionite detection. The modified carbon ceramic electrode doped with Ru-complex shows god reproducibility, a short response time (t < 2 s), remarkable long term stability (>6 month) and especially good surface renewability by simple mechanical polishing (RSD for eight successive polishing is 2%). The advantages of this sulfur compound amperometric detector based on ruthenium doped CCE are high sensitivity, inherent stability at a broader pH range, excellent catalytic activity, less expense and simplicity of preparation in comparison with recently published papers. This sensor can be used as a chromatographic detector for analysis of sulfur derivatives.