Spectroquant Pharo 300 - Page 429

Release 06/2014
Spectroquant
®
photometers NOVA 60 and Pharo photometers
Instructions for the Preparation of Standard Solutions
Standard solution of free chlorine analogous to
DIN EN ISO 7393
Preparation of a KlO
3
stock solution:
Dissolve 1.006 g of KlO
3
in 250 ml of distilled water in a calibrated or
conformity-checked 1000-ml volumetric flask. Subsequently make up to
the mark with distilled water.
Preparation of a KlO
3
/Kl standard solution:
Transfer 15.00 ml (5.00 ml) of the KlO
3
stock solution to a calibrated or
conformity-checked 1000-ml volumetric flask, add approx. 1 g of Kl and
make up to the mark with distilled water.
1 ml of this solution is equivalent to 0.015 mg (0.005 mg) of free chlorine.
Preparation of the chlorine standard solution:
Pipette 20.0 ml (10.0 ml) (full pipette) KlO
3
/Kl standard solution into a
calibrated or conformity-checked 100-ml volumetric flask, add 2.0 ml of
H
2
SO
4
0.5 mol/l, leave to stand for 1 min, and then add NaOH 2 mol/l
dropwise (approx. 1 ml) until the solution just loses its color. Subse-
quently make up the solution to the mark with distilled water.
The concentration of the solution is 3.00 mg/l (0.500 mg/l) free chlorine.
Stability:
The KlO
3
stock solution remains stable for 4 weeks when stored in a
cool place (refrigerator). The KlO
3
/Kl standard solution can be used for
5 hours when stored in a cool place (refrigerator). The diluted chlorine
standard solution is not stable and must be used immediately.
Note:
This procedure involves the preparation according to a standardized
method.
Reagents required:
1.02404.0100 Potassium
iodate, volum.
standard
1.05043.0250 Potassium iodide
for analysis
EMSURE
®
1.09072.1000 Sulfuric acid
0.5 mol/l
Titripur
®
1.09136.1000 Sodium hy-
droxide solution
2 mol/l
Titripur
®
1.16754.9010 Water for
analysis
EMSURE
®