Modeling a New Fixed‐Time Batch Approach for Mo(VI) Determination

Abstract

A fixed‐time batch approach for molybdenum determination using iodide oxidation by hydrogen peroxide is presented. The iodine formed was extracted in situ with chloroform, and the absorbance readings were performed at 510 nm. This extraction procedure allowed us to “freeze” the reaction at any preset time up to two hours, permitting a detailed investigation of the principal and interaction effects among the variables Mo(VI), H₂SO₄, H₂O_2, and KI, for the noncatalyzed and the Mo‐catalyzed reactions. Response surface methodology was employed to model this chemical system and to find its optimized conditions, resulting in a 12‐fold increase in method sensitivity. A reference material (Mussel) from the National Institute for Environmental Studies (NIES, Japan), run under the proposed conditions, gave results in good agreement with the reference value reported for molybdenum.

Keywords:

• Modeling
• in situ extraction
• kinetic‐catalytic reaction
• molybdenum determination

Acknowledgments

Thanks are due to the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for supporting the research activities of JCA. The authors also thank Prof. Carol H. Collins for reading the manuscript.