Simultaneous Determination of Cobalt and Nickel in Tin-Nickel Alloy Electroplating Solution by Two-Wavelength Spectrophotometry

The Co~(2+) and Ni~(2+) in Sn-Ni environmentally acceptable electroplating solution were simultaneously determined by means of two-wavelength spectrophotometry,using 5-Br-PADAP of a concentration(0.02)% as the color-displaying agent and tween-80 of a concentration 1% as the dissolution-promoting agent in acetic acid-sodium acetate medium of a pH value 4.5.It was found that the Bill's Law was valid when the concentration of Co~(2+) and Ni~(2+) was ranged within 0～6 μg/25 mL.The method could be readily used to determine the content of Co~(2+) and Ni~(2+) in the electroplating solution with expeditiousness and good accuracy.