Lovibond MD 100, Manual Of Methods, Page: 13 / 369

Chlorine T / M100
EN Method Reference Book 1.0 14
EN
Chlorine T M100
0.01 - 6.0 mg/l Cl
2
a)
CL6
DPD
Sampling
1. When preparing the sample, Chlorine outgassing, e.g. through the pipette or shaking,
must be avoided.
2. The analysis must take place immediately after taking the sample.
Preperation
1. Cleaning of vials:
As many household cleaners (e.g. dishwasher detergent) contain reducing
substances, this can lead to lower results with the determination of Chlorine. To avoid
measurement errors, the glassware used should be free of chlorine consumption. To
achieve this, all glassware should be placed in a sodium hypochlorite solution (0.1 g/l)
for one hour and then rinsed thoroughly with deionised water.
2. For individual testing of free and total Chlorine, the use of different sets of glassware
is recommended (EN ISO 7393-2, 5.3)
3. The DPD colour development is carried out at a pH value of 6.2 to 6.5. The reagents
therefore contain a buffer for the pH adjustment. Strong alkaline or acidic water
samples must therefore be adjusted between pH 6 and pH 7 before the analysis (use
0.5 mol/l Sulphuric acid or 1 mol/l Sodium hydroxide).