Environmental Express 99561-78, Instruction Manual, Page: 23 / 36

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Chemical Method
DPD
Interferences
Persistant Interferences
• All oxidizing agents in the samples react like chlorine, which leads to higher results.
Removeable Interferences
• Interference from Copper and Iron (III) are eliminated by the addition of EDTA.
• Concentrations above 8 mg/L Chlorine, in the event of using Powder Packs, can lead-
to results within the measuring range of up to 0 mg/L. In this case, the sample must be
diluted with chlorine-free water. 10 ml of the diluted sample should be mixed with the
reagent and the measurement taken again (plausibility test).
Method Validation
Conformity EN ISO 7393-2
Chlorine PP HR / 0.1 - 8 mg/l / CL8