双波长分光光度法测定铝合金中锌

Dual-Wavelength Spectophotomctric Determination of Zinc in Aluminium Alloy

应用锌试剂（２－羧基－２′－羟基－５′－磺苯甲Ｔｉ）作显色剂，以双波长分光光度法测定铝合金中的微量锌。在ｐＨ９．２８的条件下，选择试剂和配合物的最大吸收蜂波长（４９０ｎｍ，６２０ｎｍ）分别为参比波长和测定波长，读取吸光度差对锌浓度作图，０－２μｇ／ｍｌ范围内呈良好线性关系。由直线斜率计算摩尔吸光系数为４．４ｘ１０＾４，是单波长光度法的２倍。样品分析结果与标准值一致，相对标准偏差＜５％。

Zinc in cast aluminium alloy has been determined by dual-wavelength spectrophotometry with Zincon (2-carboxy-2'-2'-hydroxy-5'-sulformazylbenzene ). The absorbance difference at the wavelength of the zinc chelate ( 620nm ) and that of Zincon ( 490nm ) is measured. Beer's law is obeyed up to 2 ug/ml for zinc. The apparent molar absorptivity is 4.4x104. The sensitivity is two times greater than that for conventional coiorimetry.The relative standard deviation of results is less than 5%.