This article explains how chloramines can affect free chlorine validation when using DPD reference methods. It applies to Neon®/Krypton® and NEON® ONE / KRYPTON® ONE systems.
Overview
- Chloramines are a common concern when comparing online readings to DPD
- DPD 1 behavior can differ from online free chlorine measurement
- Always validate discrepancies with correct DPD procedure, timing, and reagent quality
What Are Chloramines?
Chloramines are combined chlorine species that can form when ammonia is present in chlorinated water. They are relevant in many drinking water and wastewater contexts.
Online Free Chlorine Measurement with Zirkon® DIS/ ZIRKON® ONE DIS
Kuntze free chlorine measurement has been tested by Kuntze R&D and other institutions and does not respond to and/or detect chloramines.
DPD 1 Reference Measurement (Important Difference)
DPD 1 is the most common reference method for free chlorine determination. However, ammonia and chloramines can influence the final DPD 1 result.
Many DPD reagent manufacturers include a chemical inhibitor to reduce chloramine response, but this inhibitor can be consumed within the reaction time specified by the DPD 1 procedure.
Practical Field Guidance
- If ZIRKON® DIS / ZIRKON® ONE DIS and DPD disagree, first verify DPD procedure, reagent age, and timing
- Consider chloramine influence on DPD 1 results
- For DPD limitations and reagent behavior, follow your reagent manufacturer instructions
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