Rapid measurement of trace periodate concentration with bromide ion–catalyzed periodate for oxidation colorization of DPD

Abstract

In the study, the Br−–DPD method for the determination of IO4− concentration was established. The method facilitated the DPD indicator reaction by adding Br− and DPD at pH 5.5 (50 mM phosphate buffer) to complete the measurement of the IO4− concentration. DPD+ could be detected by UV–visible spectrophotometer at 510 nm and 551 nm. The experimental results showed a strong linear relationship between the absorbance of DPD+ and the concentrations of IO4−. The slopes of the calibration standard curves for absorption wavelengths at 510 nm and 551 nm are 1.92 × 104 M−1 cm−1 (R2 > 0.999) and 2.06 × 104 M−1 cm−1 (R2 > 0.999). The stoichiometric coefficient of the Br−–DPD method for IO4− and DPD was 1:2, and pH in the range 3.0–7.0 had no significant different on the calibration curve of the Br−–DPD method. The absorbance in experimental water remained stable within 600 s. The Br−–DPD method accurately measured trace concentration of IO4− in ultrapure water at the range of 0.05 μM–10 μM. In addition, metal ions (Fe3+, Cu2+ and Co2+) and common anions (SO42−, NO3− and Cl−) showed little interference on the Br−–DPD method. The results suggested that the Br−–DPD method is a precise and versatile approach for measuring IO4− concentration.