Abstract

Regularities of the electrooxidation of sulfite ions in an alkaline medium (рН ≥ 8; LiClO₄, KNO₃, Na₂SO₄, NaOH) on a composite carbon-containing electrode modified by submicron (300 nm or smaller) gold particles are studied using cyclic voltammetry. The electrocatalytic nature of the analytical signal is substantiated; a scheme of the oxidation process is proposed. A procedure for the preliminary electrochemical treatment of the modified electrode, ensuring an increase in the substrate oxidation current and consisting in the anodic polarization of the electrode in the potential range 0.9–1.4 V (Ag/AgCl reference electrode) in a supporting electrolyte is optimized. The essence of activation is an increase in the surface area of gold particles participating in the catalytic generation/reduction cycle of gold (hydr)oxides and providing an increase in the value of the analytical signal. The proposed approach ensures a significant increase of the sensitivity of the voltammetric method for determining sulfite ions. The concentration dependence of the analytical signal is linear in the concentration range of \({\text{SO}}_{3}^{{2 - }}\)-ions 1 × 10^–7–2 × 10^–4 М (limit of detection 5.5 × 10^–8 M). The results of the determination of sulfite ions in wines, beer, and juices indicate a higher accuracy of the voltammetric method compared to the standard iodometric procedure.

中文翻译：

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亚微米金粒子修饰的复合含碳电极上亚硫酸根离子的电氧化

摘要

亚硫酸根离子在碱性介质（рН≥8; LiClO ₄，KNO ₃，Na ₂ SO _4）中的电氧化规律使用循环伏安法研究了由亚微米（300 nm或更小）金粒子改性的复合含碳电极上的NaOH）。分析信号的电催化性质得到证实；提出了一种氧化工艺方案。优化了用于修饰电极的初步电化学处理的过程，以确保增加底物氧化电流并在支持电解质中使电极的阳极极化在0.9-1.4 V（Ag / AgCl参比电极）的电位范围内。活化的本质是参与金（氢）氧化物催化生成/还原循环的金颗粒表面积的增加，并增加了分析信号的值。所提出的方法确保了伏安法测定亚硫酸根离子的灵敏度的显着提高。分析信号的浓度依赖性在浓度范围内是线性的\（{\文本{SO}} _ {3} ^ {{2 - }} \） -离子为1×10 ^-7 -2×10 ^-4 М（检测5.5×10的极限^-8 M）。葡萄酒，啤酒和果汁中亚硫酸根离子的测定结果表明，与标准碘量法相比，伏安法的准确性更高。