Environmental Express 99561-78, Instruction Manual

Page: 18 / 36

CL 200 Instruction Manual 18
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.
Preparation
1. Cleaning of vials:
As many household cleaners (e.g. dishwasher detergent) contain reducing substanc-
es, this can lead to lower results with the determination of Chlorine. To avoid measure-
ment 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 deionized 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 color 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 sam -
ples must therefore be adjusted between pH 6 and pH 7 before the analysis (use 0.5
mol/l Sulfuric acid or 1 mol/l Sodium hydroxide).
Chlorine PP HR / 0.1 - 8 mg/l / CL8