Determination of Sulfite in Real Sample by an Electrochemical Sensor Based on Ni/Poly(4-Aminobenzoic Acid)/Sodium Dodecylsulfate/Carbon Paste Electrode

In this research, a modified electrode has been produced during the electropolymerization of 4-Aminobenzoic acid in the presence of sodium dodecylsulfate (SDS) and then Ni(II) ions were incorporated to the polymer by immersion of the modified electrode in a 0.1 M Ni(II) ions solution. The electrochemical behavior of Ni/poly(4-aminobenzoic acid)/sodium dodecylsulfate/carbon paste electrode (Ni/poly(4-AB)/SDS/CPE) was investigated by using cyclic voltammetry. The experimental results exhibited the stable redox behavior of the Ni(III)/Ni(II) couple immobilized at the polymeric electrode. This polymeric modified electrode has a very good activity toward the sulfite electrooxidation in a phosphate buffer solution (pH 11). By comparison of the different responses to sulfite oxidation using electrodes Ni/poly(4-AB)/SDS/CPE, poly(4-AB)/SDS/CPE and CPE, we observed that the former electrode is a more effective catalyst for the electrooxidation of sulfite. Under optimal experimental conditions, the peak current response increased linearly with sulfite concentration over the range of 0.1-1 and 1-10 mM. The detection limit of the method was 0.063 mM. Finally, the method was applied to the determination of sulfite in weak liquor sample.