Determination of Ni Impurities Using Cadmium-Selective Electrode

Taking into account the use of Nickel brasses in industry a great number of methods for the determination of Ni have been reported. More, theoretical predictions of free Cd increasing with decreasing salinity have been confirmed using cadmium selective electrodes. The method under proposal, for the determination of nickel ions in brass alloys consists of the following steps: Cu masking with sodium thiosulfate; Ni precipitation as nickel-dimethylglyoximate at pH = 5.6 with subsequent selective extraction in chloroform; treatment of the organic phase with HNO3 1M; determination of Ni by titration of the excess of EDTA at pH = 5.6 with a solution of Cd, in the presence of the cadmium-selective electrode. The experimental values showed low dispersion and therefore a good precision. The mean value of nickel content from 13 parallel aliquots of the brass sample was 1.79% which agreed well with those obtained by the atomic absorption spectrometry, 1.77%.