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 aquacomplex 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-1levels, n= 5). The determination limits were 1.4 g Cu l-1 and 5.0 g Ni l-1 with 75 μl 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.