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在吐温20存在的碱性溶液中,铜(Ⅱ)、α,α′-联吡啶与2,2′-二氯-4,4′-二硝基重氮氨基苯(2,2′-diCl-DNAAB)迅速形成1:1:2的三元络合物(在550nm处几乎无吸收),使试剂2,2′-diCl-DNAAB的最大吸收550nm处的吸光度迅速减小,借此测定痕量铜。适宜pH为10.8—11.7;在50毫升溶液中含有1.0—2.5毫升5％吐温20、1.0—320μmolα,α′-联吡啶、2.5—5.0毫升0.2mmol/L2,2′-diCl-DNAAB、4.0—12.0毫升乙醇对吸光度无影响。铜量在0—19微克/25毫升范围服从比尔定律;表观摩尔吸光系数为1.05×10~5。考查了60种离子或化合物对测定的影响。方法应用于工业废水和铁矿中微量铜的测定,结果令人满意。
Copper (II), α, α’-dipyridyl and 2,2’-dichloro-4,4’-dinitro diazaminobenzene (2,2’- diCl-DNAAB rapidly formed a 1: 1: 2 ternary complex with little absorption at 550 nm, allowing the absorbance at a maximum of 550 nm for the reagent 2,2’-diCl-DNAAB to rapidly decrease, thereby determining Trace copper. Suitable pH is 10.8 to 11.7; 1.0 to 2.5 ml of 5% Tween 20, 1.0 to 320 μmol α, α’-dipyridyl, 2.5 to 5.0 ml 0.2 mmol / L of 2,2’-diCl-DNAAB, -12.0 ml ethanol had no effect on absorbance. Beer’s law is obeyed in the range of 0-19 μg / 25 ml of copper; the apparent molar absorptivity is 1.05 × 10-5. The effect of 60 ions or compounds on the assay was examined. The method was applied to the determination of trace copper in industrial wastewater and iron ore and the results were satisfactory.