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Analytical Method: Analytical Quality Assurance, Standard for Chlorine dioxide

Cat.No. 102404  Potassium iodate, volumetric standard
Cat.No. 105043  Potassium iodide for analysis
Cat.No. 109072  Sulfuric acid 0.5 mol/l
Cat.No. 109136  Sodium hydroxide solution 2 mol/l
Cat.No. 116754  Water for analysis
Preparation of a KlO3 stock solution:
Dissolve 1.005 g of KlO3 in 250 ml of distilled water in a calibrated or conformity-checked 1000-ml volumetric flask. Subsequently make up to the mark with distilled water.
Preparation of a KlO3/Kl standard solution:
Transfer 10.5 ml of the KlO3 stock solution to a calibrated or conformity-checked 1000-ml volumetric flask, add approx. 1.0 g of Kl and make up to the mark with distilled water. 1 ml of this solution is equivalent to 0.020 mg of chlorine dioxide.
Preparation of the chlorine dioxide standard solution:
Pipette 10 ml KlO3/Kl standard solution into a calibrated or conformity-checked 100-ml volumetric flask, add
2.0 ml of H2SO4  0.5 mol/l, leave to stand for 1 min, and then add NaOH 2 mol/l dropwise (approx. 1 ml) until the solution just loses its color. Subsequently make up the solution to the mark with distilled water. The concentration of the solution is 2.00 mg/l chlorine dioxide.
The KlO3 stock solution remains stable for 4 weeks when stored in a cool place. The KlO3/Kl standard solution can be used for 5 hours when stored in a cool place. The dilute chlorine dioxide standard solution is not stable and must be used immediately.

For use with test kits:


Measuring range
in mg/l


MColortestTM Chlorine dioxide Test

0.020 - 0.55 ClO2


MColortestTM Chlorine dioxide Test

0.50 - 28 ClO2


MColortestTM Chlorine dioxide Test refill pack for 118756



Spectroquant® Chlorine dioxide Test

0.020 - 10.00 ClO2



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