Page 111 - 20250602 EEA QM Edition 6.0

Quality Requirements Edition 6.0 European Enamel Association

Test report
Determination of the total hardness
To be mentioned are:
Take 100 ml of the water to be tested and mix it with few drops ammonia and one
Kind and origin of samples
indicator buffer tablet. Titrate with Complexon-A from red violet via grey till the colour
Place and date of test
changes into green.
Water temperature

pH-value and conductivity of water
o
ml consumption of Complexon X 5.6 = German hardness
Total-, Calcium- and Magnesium hardness

Determination of the calcium and magnesium hardness

Mix 100 ml of the water to be tested with 4 ml potash lye and 5 - 10 drops of 0.4%
Calcon carboxylic acid. In presence of Ca-ions the solution is wine red. Titrate this
with Complexon-C-solution till the colour changes into net blue.

o
ml consumption of Complexon X 2.4 = German calcium hardness

The magnesium hardness is calculated:

magnesium hardness = total hardness - calcium hardness

Required reagents
Complexon A
Indicator buffer tablets for the determination of hardness
Ammonia solution p.a. (about 25%)
Complexon C
Potash lye
50 g solid potassium hydroxide to be dissolved in
50 ml distilled water
!!! wear protective glasses !!!
Calcon carboxylic acid solution
0.4 g Calcon carboxylic acid to be dissolved in 100 ml methanol

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