Chemical Method Notes; Ph / Cyanuric Acid - ProMinent DULCOTEST DT1 Notice D'emploi

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Chemical method notes

In order to rule out this measurements error, we refer users to DIN 38 408, part 4,
No. 6.2: "The glass appliances should be free of chlorine consumption and used
exclusively for this process (determination of free chlorine and total chlorine). Chlorine
consumption-free glass appliances are obtained by placing them in a sodium
hypochlorite solution (0.1 g/l) for 1 hour and then rinsing thoroughly with water."
N.B. As an alternative to the sodium hypochlorite solution, the vial may also be
placed in chlorinated swimming pool water and then thoroughly rinsed with water
before use.
4. Preparing the sample
When preparing the sample, the escape of gases, e.g. by pipetting or shaking,
must be avoided. This applies above all to the dissolved gases chlorine dioxide
and ozone, particularly at temperatures > 30°C. The analysis must take place
immediately after taking the sample.
The DPD colour development is carried out with a pH value of 6.3-6.5. The reagents
therefore contain a buffer for the pH value adjustment. Strongly alkaline or acidic
water must, however, be neutralised before the analysis.
5. Exceeding of the measuring range
Concentrations above 10 mg/l of chlorine, 19 mg/l of ClO
produce results within the measuring range up to 0 mg/l. In this event, the water
sample must be diluted using chlorine-free water and the measurement repeated
(plausibility test).
pH
For photometric determination of pH values, only use PHENOLRED-tablets in black
printed foil pack and marked "PHOTOMETER". Water samples with low values of
Total Alkalinity-m (KS 4,3 < 0.7 mmol/l) may give wrong pH readings. The salt
content of the water also influences the result of photometric pH determination
(salt error), and the method is therefore not suitable for monitoring the function of
an electrometric pH measuring system (DIN 19 643-2 ff, No. 4.2.4. Function testing).
N.B. A plausibility test is recommended (pH meter) for results around 6.5 or 8.4, as
pH values < 6.5 or > 8.4 can produce results inside the measuring range.
Cyanuric acid
The method on hand was developed from a gravimetric process for the
determination of cyanuric acid. Based upon undefined edge conditions the
deviations of the standard method may be greater.
Method notes
Observe application options, analysis regulations and matrix effects of methods.
Reagent tablets are designed for use in chemical analysis only and should be kept
well out of the reach of children. Ensure proper disposal of reagent solutions.
and 7 mg/l of O
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