Ohura H, Imato T, Yamasaki S, Ishibashi N
Department of Industrial Chemistry, Faculty of Engineering, Kyushu Sangyo University, Matsugadai, Higashi-ku, Fukuoka, Japan.
Talanta. 1996 Jun;43(6):943-50. doi: 10.1016/0039-9140(96)01840-1.
A rapid and highly sensitive potentiometric flow-injection method for the determination of trace hydrogen peroxide was developed by use of an Fe(III)-Fe(II) potential buffer solution containing bromide and Mo(VI). The analytical method was based on a linear relationship between a concentration of hydrogen peroxide and a largely transient potential change of an oxidation-reduction potential electrode due to bromine generated by the reaction of hydrogen peroxide with the potential buffer solution. The oxidation of bromide to bromine by hydrogen peroxide occurred very rapidly with the assistance of Mo(VI) when Fe(II) existed in the potential buffer solution. It was estimated by batchwise experiments that hydroxyl radical, OH., was generated by the reaction of hydrogen peroxide with Fe(II) as an intermediate, and subsequently oxidized bromide to bromine. In a flow system, analytical sensitivities to hydrogen peroxide obtained by the detection of the transient change of potential were enhanced about 75 fold compared with those obtained by using the potential change caused by the reaction of hydrogen peroxide with the potential buffer solution without bromide and Mo(VI). Sensitivities increased with decreasing concentration of the Fe(III)-Fe(II) buffer in the reagent solution. The detection limit (S/N = 3) of 4 x 10(-7) M (13.6 ppb) was achieved by using the 1 x 10(-4) M Fe(III)-Fe(II) buffer containing 0.4 M NaBr, 1.0 M H(2)SO(4) and 0.5% (NH(4))(6)Mo(7)O(24). Analytical throughput was approximately 40 h(-1) and the RSD (n = 6) was 0.6% for measurement of 4 x 10(-6) M hydrogen peroxide. The proposed method was applied to the determination of hydrogen peroxide in real rainwater samples, and was found to provide a good recovery for H(2)O(2) added to rainwater samples.
通过使用含有溴化物和钼（VI）的铁（III）-铁（II）电位缓冲溶液，开发了一种快速且高度灵敏的电位流动注射法来测定痕量过氧化氢。该分析方法基于过氧化氢浓度与氧化还原电位电极由于过氧化氢与电位缓冲溶液反应产生的溴导致的大幅瞬态电位变化之间的线性关系。当电位缓冲溶液中存在铁（II）时，在钼（VI）的辅助下，过氧化氢将溴化物氧化为溴的反应非常迅速。通过分批实验估计，过氧化氢与作为中间体的铁（II）反应生成羟基自由基（·OH），随后将溴化物氧化为溴。在流动系统中，通过检测电位的瞬态变化获得的对过氧化氢的分析灵敏度比使用不含溴化物和钼（VI）的电位缓冲溶液与过氧化氢反应引起的电位变化获得的灵敏度提高了约75倍。灵敏度随着试剂溶液中铁（III）-铁（II）缓冲液浓度的降低而增加。使用含有0.4 M溴化钠、1.0 M硫酸和0.5%（NH₄）₆Mo₇O₂₄的1×10⁻⁴ M铁（III）-铁（II）缓冲液，实现了4×10⁻⁷ M（13.6 ppb）的检测限（信噪比=3）。分析通量约为40 h⁻¹，对于4×10⁻⁶ M过氧化氢的测量，相对标准偏差（n = 6）为0.6%。所提出的方法应用于实际雨水样品中过氧化氢的测定，发现对添加到雨水样品中的过氧化氢具有良好的回收率。
