超高灵敏卟啉试剂导数分光光度法直接测定矿样中的痕量铜

Direct Determination of Trace Copper in Mineral Samples by Derivative Spectrophotometry Using Porphyrin Reagent

用ｍｅｓｏ－四－（对－三甲铵苯基）卟啉作显色剂，以四阶导数光谱技术进行测量，提出了测定痕量钢的新方法。在ｐＨ４．４的ＨＡｃ－ＮａＡｃ介质中，在盐酸羟胺催化和乙醇增稳增敏作用下，于沸水浴中加热１ｍｉｎ，显色反应即可完成。其四阶导数光谱表观摩尔吸光系数ε’达１．００×１０７Ｌ· ｍｏｌ－１· ｃｍ－１，最低检出限为 ０．０６２μｇ／Ｌ，分别是常规光度法的２１．２和１２．３倍。同时，绝大多数离子不干扰测定，轻微混浊也无影响；在选定条件下，导数值与铜浓度在０～４μｇ／Ｌ范围内呈良好的线性关系（ｒ＝０．９９９９）。该法用于地矿样品中痕量钢的不分离直接测定，结果与推荐值相差－４．４％～５．３％。

A method for the determination of trace copper has been developed by using 4th derivative spectrophotometric technique and meso-tetrakis-(4-trimethylammoniumphenyl)- porphyrin as color reagent.Based on the catalytic action of hydroxylamine hydrochloride and on the stabilization and sensitization of alcohol, the chromogenic reaction can progress quan- titatively in pH 4.4 HAc-NaAc buffer medium and in a boiling water-bath for 1 min. The 4th-derivative spectral molar responsive coefficient and the detection limit for copper are 1. 00×107L. mol-1. cm-1 and 0.062 μg/L, which is 21.2 times as high and 12.3 times as low as that of ordinary spectrophotometry, respectively. Most of ions and slight turbid don't in- terfere with the determination; and the copper ion concentration from 0 to 4 ug/L has a good correlation with the 4th derivative values (r=0.9999) under the selected conditions. The proposed method has been applied to the direct determination of trace copper in geochemical samples, and the differences between the determined results and the certified values are within ±5%.