Water I.D. Primelab 2.0, Manual

Page: 154 / 301

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.
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.
Turbidity caused by high concentration of calcium ions will affect the measurement result. To
prevent that, please use DPD HC (High Calcium) reagents.
T99/204 T99/204