Can the free DPD chlorine test kit or instrument measure chlorine dioxide using a conversion from chlorine to chlorine dioxide?

Document ID

Document ID TE223

Published Date

Published Date 19/05/2019
Question
Can the free DPD chlorine test kit or instrument measure chlorine dioxide using a conversion from chlorine to chlorine dioxide?
Summary
Using Free Chlorine DPD for chlorine dioxide
Answer
A DPD Free Chlorine test kit or instrument should not be adapted for measuring chlorine dioxide, even using the glycine reagent. This is because the calibration curve for Chlorine Dioxide is not linear, while the Free Chlorine curve is. Therefore a single conversion factor cannot be used unlike other oxident conversion factors.