5-Br-PADCAP分光光度法测定铝合金中的微量锌

Spectrophotometric Determination of Micro Zinc ( Ⅱ ) in Aluminium Alloys with 5-Br-PADCAP

本文报导了新显色剂2-(5-溴-2吡啶偶氮)-5-[(N,N-二羧基甲基)氨基]苯酚(5-Br-PAD-CAP)的合成以及与锌的显色反应.在pH9.2试剂和络合物的最大吸收波长分别为457.6nm和563.8nm.络合物的表观摩尔吸光系数ε_(564)nm=1.21×10~5L·Mol^(-1)·cm^(-1).用等摩尔连续变化法和摩尔比法测得5-Br-PAD-CAP与Zn(Ⅱ)络合物的络合比为2:1,求得络合物的表观稳定常数K=1.7×10^(13)采用717阴离子交换树脂分离的方法来消除干扰,使锌与铝、铁等元素分离.所建立的方法应用于铝合金中微量锌的测定,结果与AAS很一致;回收率为99.0%～101.4%.

A color reaction of zinc( II )with a new reagent, 2- ( 5-bromo-2-pyridylazo ) -5-C(N, N-dicarboxymethyl )amino]-phenol ( 5-Br-PADCAP ) , and its optimum conditions have been investigated. It has been shown that the maximum absorption wavelengths of the reagent and the complex are 457.6nm and 563.8nm respectively at pH9.2. The composition ratio of Zn( II )to 5-Br-PADCAP is 1 : 2 and the apparent stability constant is 1.7×1018. The apparent molar absorption coefficient is 1.21×105. Beer's law is obeyed in concentration range of 0-20 ug/25ml for Zn(II) with a r of 0. 9998. The interfering ions are separated by an ioaic exchange resin. This method has been used to determine micro Zn( II )in aluminium alloys. The results are favorable agreed with that obtained by AAS.