Determination of copper and nickel ion in copper electrolyte by a flow-injection spectrophotometric method

A fully automated flow-injection system for the spectrophotometric determination of copper and nickel ions in copper electrolyte has been developed. To detect each aqua-complex by utilizing one spectrophotometer, at first, the sum of the absorbance of copper and nickel ions was measured at a reference-path. After mixing a thiourea solution to mask copper ions as the copper-thiourea complex, the absorbance of nickel ion was measured at the sample-path. The concentrations of each element were calculated from the difference of each absorbance and from a dilution factor between the two paths. The reproducibility has been proven to be satisfactory with relative standard deviations of less than 0.8% (RSD, 30 g Cu l(-1)-15 g Ni l(-1) levels, n = 5). The determination limits were 1.4 g Cu l(-1) and 5.0 g Ni l(-1) with 75 mu l sample injection. This system permits a throughput of 30 samples per hour. It is suitable for monitoring the concentration of copper and nickel ions in a copper electrolytic process stream.