Tintometer Lovibond MD100 Manual página 18

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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
CrO
2-
4
MnO
2
Method Validation
Limit of Detection
Limit of Quantification
End of Measuring Range
Sensitivity
Confidence Intervall
Standard Deviation
Variation Coefficient
Conformity
EN ISO 7393-2
a) determination of free, combined and total
EN Method Reference Book 1.0
from / [mg/l]
0.01
0.01
0.02 mg/l
0.06 mg/l
6 mg/l
2.05 mg/l / Abs
0.04 mg/l
0.019 mg/l
0.87 %
Chlorine T / M100
EN
19