Determination of additives in an electrolytic zinc bath by qH-NMR spectroscopy.

Barriola, Ainara; Miranda, José I.; Ostra, Miren; Ubide, Carlos

The use of proton nuclear magnetic resonance (H-NMR) for the quantification of additives in an electrolytic Zn bath is reported. A simple and quick method is described that does not need any prior sample preparation. Contrary to other analytical methods, the three additives in the bath, benzylidene acetone (BDA), benzoic acid (BA) and poly(ethylene glycol) (PE400), can be quantified. Two calibration methods were tried: integration of NMR signals with the use of an internal standard and partial least squares (PLS) regression applied to the characteristic NMR peaks. Both methods are compared and the univariate method was preferred because of simplicity, accuracy and precision. The following limits of detection were found: 0.30 g L BA, 0.08 g L BDA and 0.7 g L PE400 with dynamic ranges of at least 1.0–6.0, 0.1–0.6 and 3.0–18.0 g L respectively. Those concentration ranges are suitable to follow the concentration of additives in the bath in real time. H-NMR spectra provide evidence for the BDA degradation pattern. [Figure not available: see fulltext.]

MAGNETIC resonance; ELECTROLYTIC iron; ZINC; ELECTROPLATING; SPECTRUM analysis

Analytical & Bioanalytical Chemistry, 2010, Vol 398, Issue 2, p1085

1618-2642

Academic Journal

10.1007/s00216-010-4003-2