A Box-Behnken Design and Response Surface Approach for the Simultaneous Determination of Chromium (III) and (VI) Using Catalytic Differential Pulse Polarography

The present paper describes an optimized Box-Behnken design using a catalytic-differential pulse polarograhic technique for the simultaneous determination of chromium (III) and (VI) in wastewater samples using ammonium piperidine dithiocarbamate as a complexing agent. The optimization strategy was carried out using a two level full factorial design. The results of the experimental design were based on an analysis of variance and demonstrated that only the pH, concentrations of the buffer and the complexing agent were statistically significant throughout the experiment. The optimal values for the three variables were 8.0, 0.2 mM and 5.0 mM for pH, concentrations of the buffer and the complexing agent respectively. Under optimum experimental conditions the detection limit of the proposed method was found to be 0.0841 µg L-1 while the linear range was 1.0-10.0 and 0.5-25.0 µg L-1 for chromium (III) and (VI) respectively. The present method was also applied for the simultaneous determination of chromium in the presence of some foreign ions with satisfactory analytical responses