Lovibond MD 110 - Page 18

Chlorine T / M100
ENMethod Reference Book1.0 19
EN
Chemical Method
DPD
Appendix
Interferences
Persistant Interferences
• All oxidising 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.
• The use of reagent tablets in samples with high Calcium content* and/or
high conductivity* can lead to turbidity of the sample and therefore incorrect
measurements. In this case, the alternative reagent tablet DPD No. 1 High Calcium
and reagent tablet DPD No. 3 High Calcium should be used.
*it is not possible to give exact values, because the development of turbidity depends
on the composition and nature of the sample.
• Concentrations above 10 mg/l Chlorine, in the event of using fluid reagents, can
lead to results within the measuring range of up to 0 mg/l. In the event of a high
concentration of Chlorine, 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).
Interference from / [mg/l]
CrO
4
2-
0.01
MnO
2
0.01
Method Validation
Limit of Detection 0.02 mg/l
Limit of Quantification 0.06 mg/l
End of Measuring Range 6 mg/l
Sensitivity 2.05 mg/l / Abs
Confidence Intervall 0.04 mg/l
Standard Deviation 0.019 mg/l
Variation Coefficient 0.87 %
Conformity
EN ISO 7393-2
a)
determination of free, combined and total