Determination of copper and zinc in metallurgical products by automatic derivative spectrophotometric titrations

Direct automatic derivative spectrophotometric titration procedures for copper and zinc in brasses and bronzes are described. Copper reacts with excess iodide and the liberated iodine is automatically titrated with thiosulfate using the UV absorption band of iodine for end-point detection. Total copper and zinc is automatically titrated with EDTA using PAN as indicator, and zinc is found by difference. 'I'he automatic termination of the titrations eliminates the subjective evaluation of the end-points, and the entire procedure is simple, precise and accurate. The total time required for determining copper and zinc in brass or bronze is about twenty minutes.