Determination of Ni2+ Impurities Using Cadmium-Selective Electrode

Taking into account the use of Nickel brasses in industry a great number of methods for the determination of Ni2+ have been reported. More, theoretical predictions of free Cd2+ 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: Cu2+ masking with sodium thiosulfate; Ni2+ precipitation as nickel-dimethylglyoximate at pH = 5.6 with subsequent selective extraction in chloroform; treatment of the organic phase with HNO3 1M; determination of Ni2+ by titration of the excess of EDTA at pH = 5.6 with a solution of Cd2+, 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%