Simultaneous electroanalysis of hypochlorite and H2O2:: Use of I-/I2 as a probing potential buffer
Simultaneous electroanalysis of hypochlorite and H2O2:: Use of I-/I2 as a probing potential buffer
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DOI：
10.1002/elan.200403151
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发表时间：
2005-05-01
期刊：
影响因子：
3
通讯作者：
Ohsaka, T
中科院分区：
文献类型：
--
作者：
Awad, MI;Sata, S;Ohsaka, T
本文首次采用简单快速的电位法同时分析了次氯酸钠（NaClO）和过氧化氢（H2O2）。该方法灵敏度高，选择性好，重现性好。Pt电极作为指示电极，I-2/I-氧化还原偶对作为探测电位缓冲。两种氧化剂对I-的氧化速率差异很大，也就是说，两种氧化剂对I-的氧化速率差异较大。NaClO对I-的氧化比H2O2的氧化快几个数量级，使这两种物质的选择性分析成为可能。基于如此大的速率差异，可以得到I-被NaCIO氧化的瞬时电位响应和另一个被H2O2氧化的相当慢的电位响应。考察了影响选择性和灵敏度的因素，如电位缓冲液中钼酸盐（用作H2O2氧化I-的催化剂）、H+-、12和I-的浓度。在相当大的浓度范围内，nacl和H2O2的斜率分别为30.5 mV和29.9 mV（与理论值接近，即29.6 mV），并且检测限在亚微摩尔范围内（0.2 μ M），获得了预期的Nernstian响应。
Sodium hypochlorite (NaClO) and hydrogen peroxide (H2O2) have been simultaneously analyzed, for the first time: using a simple and rapid potentiometric method. The present method shows a high sensitivity, selectivity and satisfactory reproducibility. Pt electrode was used as an indicator electrode and the I-2/I- redox couple was used as a probing potential buffer. The large difference in the rates of the oxidation of I- by the two oxidizing agents, that is, the. oxidation of I- by NaClO is by several orders of magnitude faster than that by H2O2, enabled the selective analysis of these two species. Based on such a large difference in the rates, a momentary potential response corresponding to the oxidation of I- by NaCIO and another quite slow one by H2O2 could be obtained. Factors affecting the selectivity as well as the sensitivity, such as the concentrations of molybdate (used as catalyst for the oxidation of I- by H2O2), H+-, 12, and I- in the potential buffer were examined. The expected Nernstian responses were obtained over a considerable range of the concentrations of the two oxidizing agents with slopes of 30.5 and 29.9 mV for NaClO and H2O2, respectively (in a close agreement with the theoretical value, that is, 29.6 mV) and with a detection limit in the submicromolar range (0.2 mu M).