Distinguishing three halate anions by using a pH clock system

In this study, we report an electrochemical method for the identification of three halates (ClO 3 − , BrO 3 − , and IO 3 − ) by using a pH clock system composed of HCHO-NaHSO 3 -Na 2 SO 3 . When equal amounts of analytes (halates) are separately added to the clock system, the increase in the induction period for the clock system is observed to be IO 3 − > BrO 3 − > ClO 3 − . Three halates are then distinguished from each other by such different perturbation effects. Furthermore, there is a linear relationship between the concentration of halates and the induction period in the range of 5.0 × 10 −4 -2.0 × 10 −3 mol/L. The quantitative analysis for halates is then to be achieved. Finally, the perturbation mechanisms of the three halates on the pH clock system are explained in detail.