Do not clean glassware and equipment with household detergents, as these could greatly
reduce the measurement result. To prevent any contamination, the cuvette, lid and stirrer
should be stored in a 0.1 % sodium hypochlorite solution for one hour. Then rinse with distilled
water, thoroughly.
Water samples with a high calcium content resp. a high conductivity will render the sample
cloudy, which is detrimental to the measurement precision. In this case use "DPD N°1 High
Calcium (HC)" reagents.
If the sample water contains more than 40 mg/l bromine, a measured value of 0 mg/l can be
displayed. In that case, a dilution is recommended.
The DPD reagent buffers the pH value of the sample water in the range of 6.2 to 6.5, which is
essential for colour development. If the sample water is very alkaline or acidic, this must be
adjusted to a pH within the range of 6 to 7 by addition of 0.5 mol/l sulphuric acid or 1 mol/l
caustic soda, respectively, before the DPD reagent is added.
If the sample water contains further oxidizing agents, these will react like bromine and
contribute to the measurement result.
T14/204 T14/204
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