| Summary: | A cyclic voltammetry (CV) and differential pulse cathodic stripping voltammetry (DPCSV) studies of RB5 in Britton-Robinson buffer (BRB) at a hanging mercury dropping electrode (HMDE) are described. CV was carried out by cathodic and anodic potential scan over the range of +200 mV to -800 mV with no accumulation time and three well-defined pH-dependent cathodic peaks were observed. The effects of different scan rates, pH of BRB, repetitive cycle and increasing concentrations on the peak height and peak potential of the analyte were studied. The results showed that RB5 dye was adsorbed and irreversibly reduced at the mercury electrode, mainly under diffusion controlled in the optimum pH 4.0 of BRB. By using DPCSV, pH of BRB and various instrumental parameters such as scan rate, accumulation time, accumulation potential and pulse amplitude that may affect the peak height of RB5 were investigated and optimized for RB5 determination. Under the optimized parameters, the peak height was found to be linear with RB5 concentration in the range from 2.5 × 10-7 mol L-1 to 2.0 × 10-6 mol L-1. A detection limit (3SD/m) of 1.3 × 10-8 mol L-1 was achieved. The precision of the developed method in terms of RSD was 0.55% for intra-day measurement and 0.55%, 0.24% and 0.40%, for inter-day measurements, respectively. The developed method was successfully applied in the determination of RB5 in batik wastewaters with the mean recovery of 83.97 ± 4.78% to 97.93 ± 5.45% (0.5 × 10-6 mol L-1), 95.91 ± 2.68% to 103.49 ± 1.32% (1.0 × 10-6 mol L-1) and 99.17 ± 0.75% to 105.12 ± 0.28% (2.0 × 10-6 mol L-1). The developed method is considered sensitive, precise, accurate, rugged, robust, fast and low cost for routine analysis of RB5 dye in batik wastewaters over the UV-VIS spectrometry method. © 2016, Malaysian Society of Analytical Sciences. All rights reserved.
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