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 chlorine, 19 mg/l chlorine dioxide and 4.75 mg/l
chlorite can produce results within the measuring range of up to 0 mg/l. In this
event, the water sample must be diluted using chlorine-free water and the
measurement repeated (plausibility test).
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.
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Consumables/ Spare parts
stirrer for stripping the chlorine dioxid, order no. 1022754
3 off spare cells (measuring cell (cuvette) for fotometer) order no. 1007566
DPD reagent set each 15 ml, order no. 1007567
3x DPD1 buffer, 1x DPD 1 reagent, 1x DPD 3 solution
DPD1 buffer, order no.1002857
DPD 1 reagent, order no. 1002858
DPD 3 Solution, order no.1002859
Chlorine dioxide tablet Nr.1 R 127, order no. 501317
Chlorine dioxide tablet Nr.2 R 128, order no. 501318
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