For the determination of low concentrations (up to 2.5 mg/l) of chlorine dioxide (CIO2) and chlorite, the photometric or colorimetric DPD methods are well established. Higher concentrations of ClO2, which are present in concentrates, must be determined by titration with sodium thiosulphate (Na2S2O4) or after strong dilution.
Determination of chlorine dioxide in disinfectants.
Suitable for all solutions containing chlorine dioxide (ClO2).
For the determination of low concentrations (up to 2.5 mg/l) of chlorine dioxide (CIO2) and chlorite the photometric or colorimetric DPD methods are well established. Higher concentrations of ClO2 that are present in the concentrates have to be determined by titration with sodium thiosulphate or after strong dilution.
Chlorine dioxide oxidizes iodide to iodine, which is then reduced by sodium thiosulphate. The sodium thiosulphate consumed is recalculated as ClO2.
|
2 ClO2 + 2 NaI |
→ |
I2 + 2 NaClO2 |
|
I2 + 2 Na2S2O3 |
→ |
2 NaI + Na2S4O6 |