碘化物-结晶紫-聚乙烯醇体系分光光度法测定自来水中痕量二氧化氯

Spectrophotometric Determination of Trace Chlorine Dioxide in Tap Water with Iodide-Crystal Violet-Polyvinyl Alcohol System

在稀磷酸介质中，二氧化氯（ＣｌＯ２）氧化Ｉ离子形成 Ｉ３配阴离子，Ｉ３进一步与结晶紫（ＣＶ）阳离子形成离子缔合物［ＣＶ］［Ｉ３」。在聚乙烯醇存在下，该离子缔合物最大吸收波长λｍａｘ位于５５２ ｎｍ处，摩尔吸光系数ε＝２５ × １０５Ｌ·ｍｏｌ－１·ｃｍ－１，对 ＣｌＯ２的检出限为 ０．６ μｇ／Ｌ，线性范围是 ０．６～２８０μｇ／Ｌ。加入适量 ＫＦ溶液可消除自来水中Ｆｅ（Ⅲ）的干扰。方法对μｇ／Ｌ级ＣｌＯ２ 的测定有较好的选择性，可成功地用于自来水样品分析。

A highly sensitive spectrophotometric method has been developed for the determination of ClO2, based on the oxidation of I- to I-3(-) by ClO2 and the further reaction of I-3(-) with crystal violet to form the ion-association complex [CV] [I-3] in dilute phosphoric acid medium. The lambda(max) of the ion-association complex is 552 run (against reagent blank), the molar absorptivity is 2.5 x 10(5)L.mol(-1).cm(-1), the detection limit of ClO2 is 0.6 mug/L and the linearity range is 0.6 similar to 280 mug/L. The interference of Fe(III) is eliminated by adding potassium fluoride to the sample solution, so the determination method has good selectivity. ClO2 at mug/L levels in tap water has been determined by the method satisfactorily.