二溴对氯偶氮羧胂分光光度法测定微量铅

Spectrophotometric determination of micro lead with 2,6-dibromo-4-chloro-carboxylarsenazo as chromogenic reagent

研究了显色剂二溴对氟偶氮羧胂与微量铅的显色反应条件。在0．04～0．24mol／L硫酸介质中，铅（Ⅱ）与显色剂形成蓝紫色络合物，最大吸收波长为620nm，表观摩尔吸光系数ε=4.51×10^4 L·mol^-1·cm^-1，在25mL溶液中，铅的质量在0～25μg范围内符合比尔定律。方法具有较高的选择性，与其它已报道方法相比共存离子铜、锌、铝有更大的允许量。用于铜合金和铝黄铜标准样品中微量铅的测定，结果与认定值相吻合，相对标准偏差分别为1．4％和2．0％。

The color reaction conditions of micro lead with 2,6-dibromo-4-chloro-carboxylarsenazo （DBC- CA） were studied, h was found that in 0.04- 0.24 mol/L H2SO4 medium,lead（U） formed a blue complex with DBCCA.The apparent molar absorptivity is 4.51× 10^4 L·mol^-1· cm^-1 at 620 nm. Beer＇s law is obeyed for lead in the range of 0 - 25 μg/25 mL. The method has more selectivity and tolerance amount of foreign ions i.e. Cu^2 ＋ ,Zn^2＋ and A^13 ＋ than another reported. It has been satisfactorily applied to determine lead in copper alloy and aluminum brass samples, and the results were in good agreement with the certified values, the RSD （ n = 5）of the results was 1.4 % and 2.0 %.