Aplication of Box-Behnken Design to Optimize the Coprecipitation Parameters to Assess As and Cd Contamination in Marine Fish

Abstract

A Box-Behnken design approach was used to plan the experiments for As and Cd determination in fish samples. It combines microwave-induced plasma optical emission spectrometry (MIP OES) with silver nitrate and potassium chromate coprecipitation. Multiple Response methodology (MR) has been adopted to express the output parameters (responses) that are decided by the input process parameters. MR also quantifies the relationship between the variable input parameters and the corresponding output parameters. Factors that directly affect the coprecipitation procedure, such as silver and chromate concentrations and solvent volume, were optimized. The optimized conditions were 5.46 x10− 4 mol L− 1 [CrO42−] and 1.16 x10− 3 [Ag+], without needed of solvent addition. The procedure provided preconcentration factors of 25 and 11 for As and Cd, respectively, and LOD adequate to the international legislation. The trueness was assessed with the analysis of certified reference materials (CRMs) and compared with inductively coupled plasma mass spectrometry (ICP-MS). Relative standard deviations < 9% and 3.5% and recoveries > 91% and 88% were obtained for As and Cd, respectively. The method was applied to local market fish samples and showed suitability for As and Cd determination by MIP OES.