Analytical control of nickel coating baths by digital image analysis

Abstract

Nickel plating is a widely employed technique. To carry out this, nickel baths are used, which require a great control of the concentration of its components. In this work, fast and cheap methods based on digital image analysis (DIA) are proposed to determine some of the major compounds in these baths such as nickel, ammonium and sulfate ions. The greatest advantage of these methods is the possibility of analyzing several samples at the same time using very small volumes, lower than 400 μL. Simple and widespread equipment as a desktop scanner has been used to obtain the digital images. Using these images, linear regression models were built for each analyte, obtaining correlation coefficients higher than 0.99, RSD values lower than 14.0% and recoveries between 82 and 111% in all cases. The reproducibility of the images has been confirmed by a color standard. These methods have been applied successfully in real samples. The results obtained have been compared with reference techniques, such as UV–Vis spectrophotometry, ion chromatography and potentiometry. No significant differences were observed between these methods and the proposed digital image analysis method.