Quantitative determination of additives in a commercial electroplatingnickel bath by spectrophotometry and multivariate analysis

Abstract

An electroplating nickel bath is usually composed of a number of organic additives to improve the plating process as well as to preserve its durability. Supreme Plus Brightener (SPB) and A-5(2X), used in a commercial electroplating nickel bath show highly overlapped UV-Vis spectra. These two additives are the only ones that present absorbance in the UV-Vis wavelength range. Therefore, a mixture of them can be resolved using multivariate calibration methods of UV-Vis measurements. In this work, Partial Least Squares (PLS) regression and Classical Least Squares (CLS) have been used to quantify both additives during the whole duration of an electroplating nickel bath. It was found that PLS regression provided the best results. To avoid negative influence of baseline drifts, first derivative spectra were used. Between 0.14 and 1.40 mL of the commercial product SPB per L of nickel bath can be determined with mean errors of about 6%. Between 4 and 24 mL of the commercial product A-5(2X) per L of nickel bath can be determined with mean errors of about 8%. The limits of detection (LOD) found for SPB and A-5(2X) were 0.11 mL L À1 and 3 mL L À1 respectively. The calibration models proved to be valid for at least eight months, including a change of spectrophotometer. The SPB concentration decays along the bath life according to a first order rate law, but A-5(2X) remains unchanged. Independent brightness measurements showed that it was intimately related to the SPB concentration, in such a way that any of them can be deduced from the other one. This is of prime importance to keep the bath conditions under control.

Review of the Application of Near-Infrared Spectroscopy Technology to Determine the Chemical Composition of Animal Manure

“…The noise contained in the spectral information is one of key factors significantly influencing the prediction of NIRS analysis. Chemometrics, which involves spectra preprocessing and multivariate calibration methods, is an efficient tool to eliminate or reduce spectra noise and improve NIRS prediction (Azzouz et al, 2003; Vidal et al, 2010). In most previous studies, the most common preprocessing methods, such as standard normal variate, multiplicative scatter correction, derivative, and smoothing, were usually used.…”

Gas chromatography with flame ionization detection for determination of additives in an electrolytic Zn bath

“…UV-Visible spectroscopy, together with classical least squares (CLS) or inverse least squares (ILS) calibration, was used for determination of additives in Ni-Zn baths [3]. More recently, additives in Ni baths have also been determined using UV-Visible spectroscopy with partial least squares (PLS) calibration [4]. The use of NMR spectroscopy to follow the additive behavior in an electrolytic Zn bath [5] and the potential of this technique for the quantitation of additives in an acidic Zn bath has also been shown [6].…”

Influence of Operation Parameters on Metal Deposition in Bright Nickel-plating Process

“…Three kind of additives were included in the model in order to control the local surface growth rate. Partial least square (PLS) regression and classical least square (CLS) were used by Vidal et al [12] to quantify both additives during the whole duration of electroplating nickel bath. It was found that PLS regression provided the best results.…”