Costa A C, Ferreira S L, Andrade M G, Lobo I P
Instituto de Química, Universidade Federal da Bahia, Campus Universitário da Federação-40210 Brazil.
Talanta. 1993 Aug;40(8):1267-71. doi: 10.1016/0039-9140(93)80197-y.
The reaction of nickel (II) with Br-PADAP, in the presence of tergitol NPX surfactant, forms a complex with absorption peaks at 520 and 560 nm. The iron(II)-Br-PADAP system at the same conditions forms a chelate with absorption peaks at 560 and 748 nm. This allows the simultaneous spectrophotometric determination of nickel and iron by measuring the absorbance at 560 and 748 nm. The proposed method, at ph 4.0-5.7, shows a molar absorptivity of 1.22 x 10(5)l . mole(-1) . cm(-1) for nickel at 560 nm and 8.20 x 10(4)l . mole(-1) . cm(-1) at 560 nm and 3.35 x 10(4)l . mole(-1) . cm(-1) at 748 nm for iron(II). Beer's law is obeyed up to 0.40 mu/ml of nickel(II) and up to 0.65 mu/ml of iron(II). Thiosulphate as masking agent allows the simultaneous determination of iron and nickel in the presence of high concentrations of copper. The ethylene glycol 2-(2-amino-ethyl) tetracetic acid provides the elimination of many other interferences. The method has been applied successfully to the simultaneous determination of nickel and iron in reference samples.
在壬基酚聚氧乙烯醚（Tergitol NPX）表面活性剂存在下，镍（II）与溴邻苯三酚红（Br-PADAP）反应形成一种配合物，其吸收峰位于520和560 nm处。在相同条件下，铁（II）-溴邻苯三酚红体系形成一种螯合物，吸收峰位于560和748 nm处。这使得通过测量560和748 nm处的吸光度能够同时分光光度法测定镍和铁。所提出的方法在pH 4.0 - 5.7时，对于镍在560 nm处的摩尔吸光率为1.22×10⁵ l·mol⁻¹·cm⁻¹，对于铁（II）在560 nm处为8.20×10⁴ l·mol⁻¹·cm⁻¹，在748 nm处为3.35×10⁴ l·mol⁻¹·cm⁻¹。镍（II）浓度在0.40μg/ml以下、铁（II）浓度在0.65μg/ml以下时符合比尔定律。硫代硫酸盐作为掩蔽剂可在高浓度铜存在下同时测定铁和镍。乙二醇双（2-氨基乙基）四乙酸可消除许多其他干扰。该方法已成功应用于参考样品中镍和铁的同时测定。
