表面活性剂存在下，以3，5－di－Cl－PADAP分光光度法测定微量铁的研究

Study on the spectrophotometric determination of micro amounts of iron(Ⅱ) with 3,5-di-CI-PADAP in the presence of emulsifierOP

研究了２－（３，５－二氯－２－吡啶偶氮）－５－二乙氨基酚（３，５－ｄｉ－Ｃｌ－ＰＡＤＡＰ）与Ｆｅ（Ⅱ）的显色条件。在非离子表面活性剂乳化剂ＯＰ存在下，于ｐＨ３．５～６．０的乙酸钠－乙酸缓冲介质中，Ｆｅ（Ⅱ）与３，５－ｄｉ－Ｃｌ－ＰＡＤＡＰ的络合反应瞬时完成，形成１：２的紫红色稳定的络合物，该络合物有两个最大的吸收峰分别为５７０ｎｍ和７５５ｎｍ，相应的表观摩尔吸光系数分别为８．４×１０４和３．９×１０４，铁含量在０～２０μｇ／１０ｍＬ范围内符合比尔定律。选用７５５ｎｍ作为工作波长，可高选择性地测定多种样品中的微量Ｆｅ（Ⅱ），方法灵敏、操作简便、结果满意。

The colour reaction of Fe(Ⅱ) with 3,5-di-ClPADAP in the presence of emulsifier OP was studied.In a buffer medium with PH range of 3.5～6.0, Fe(Ⅱ)reacts with 3,5-di-Cl-PADAP to form a 1:2 stable complex, exhibiting two absorption maxima at570nm and 755nm respectively. The apparent molarabsorytivity was found to be 3. 9×104L· mol-1· cm-1 at755nm. Beer's law is obeyed for 0～20μg of iron(Ⅱ)in 10mL of solution. The method is highly selective for Fe(Ⅱ). It was applied to the spectrophotometric determination of micro amounts of iron(Ⅱ) inchemical reagents, water, ore sample, alloy andvarious biological samples with satisfactory results.