Potassium bromate assay by primary methods through iodine liberation reaction

Analyses of bromate are of interest, especially from the viewpoint of controlling water and food quality. Currently, the lack of a potassium bromate reference material creates problems for the reliability of analytical measurements in those areas. Bromate whose concentration is traceable to the International System of Units (SI) is needed to ensure accurate and reliable measurements around the globe; however, no one has given the procedure of an accurate assay. Several document standards and texts describe the procedure of the titration and require different, insufficient titration conditions; the authors clarified an appropriate set of titration conditions. This paper describes the measurement procedure and assay of bromate with the linkage to the SI by primary methods. Gravimetric titration with thiosulfate whose concentration was standardised by coulometric titration with electrogenerated iodine was applied to the assay of bromate through the iodine liberation reaction. The appropriate iodine liberation conditions to titrate potassium bromate with sodium thiosulfate were clarified through examinations by electrochemical methods. Finally, an accurate determination method for bromate was first established with high accuracy and traceability to the SI by primary methods.