Lovibond MD 610, Instruction Manual

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125
MD 610_1c 09/2015
Notes:
1. The hydrogen peroxide is determined in the form of yellow/orange coloured peroxotitanic
acids in strongly acidic media. In connection with neutral to weakly alkaline (~pH 10)
samples, the acid in the reagent is sufficient in order to produce a medium suitable for
measurement. In the case of strongly alkaline samples (pH > 10), the samples must be
acidified before measurement otherwise the results may be deficient. This is achieved
by diluting the sample with a 5% sulphuric acid solution, for example, at a ratio of 1:1.
In contrast to many other colour reactions, in connection with the presence of hydrogen
peroxide, discoloration with long-term stability is achieved that can still be measured
after 24 h. Particles in the sample solution or turbidity distort the analysis and must be
eliminated by centrifuging or simply filtering the sample solution prior to performing the
measurement. Falsification of the measurement results should also be expected in connection
with coloured solutions.
2. Oxidising agents such as chlorine, bromine, chlorine dioxide and ozone do not distort the
analysis. On the other hand, however, water discoloration does distort the analysis. In this case,
proceed as described in the following:
• Fill a clean vial (16 mm Ø) with 10 ml of the water sample and perform zero calibration
(see “Operation”).
• Measure the sample solution without the addition of drops of reagent ( result B).
• Then the same sample solution, measured with the addition of the reagent drops
( result A).
• Calculations: mg/l H
2
O
2
= result A – result B
3. Attention: The reference reagent contains a 25% sulphuric acid solution. It is recommended
to wear appropriate protective clothing (protective goggles/gloves).
Reagent Form of reagent/Quantity Order-No.
H
2
O
2
-reagent Liquid reagent / 15 ml 424991