wtw PhotoLab Spektral Operating Instructions Manual page 24

Instructions for the Preparation of Standard Solutions
Standard solution of chlorine dioxide
acc. to DIN EN ISO 7393
Preparation of a KlO
Dissolve 1.005 g of KlO
water in a calibrated or conformity-checked
1000-ml volumetric flask. Subsequently make up
to the mark with distilled water.
Preparation of a KlO
Transfer 10.5 ml of the KlO
calibrated or conformity-checked 1000-ml
volumetric flask, add approx. 1g of Kl and make
up to the mark with distilled water.
1 ml of this solution is equivalent to 0.020 mg
of chlorine dioxide.
Preparation of the chlorine dioxide
standard solution:
Pipette 10 ml KlO /Kl standard solution into a
3
calibrated or conformity-checked 100-ml
volumetric flask, add 2.0 ml of H
leave to stand for 1 min, and then add NaOH
2 mol/l dropwise (approx. 1 ml) until the solution
just loses its colour. Subsequently make up the
solution to the mark with distilled water.
The concentration of the solution is 2.00 mg/l
chlorine dioxide.
Stability:
The KlO stock solution remains stable for 4
3
weeks when stored in a cool place. The KlO
standard solution can be used for 5 hours when
stored in a cool place. The dilute chlorine dioxide
standard solution is not stable and must be used
immediately.
Reagents required:
1.02404.0100 Potassium iodate, volum. standard
1.05043.0250 Potassium iodide GR for analysis
1.09072.1000 Sulfuric acid 0.5 mol/l
1.09136.1000 Sodium hydroxide solution 2 mol/l
1.16754.9010 Water GR for analysis
XXII
stock solution:
3
in 250 ml of distilled
3
/Kl standard solution:
3
stock solution to a
3
SO 0.5 mol/l,
2 4
3
Standard solution of COD
Preparation of a standard solution:
Dissolve 0.850 g of potassium hydrogen phthalate
GR in a calibrated or conformity-checked 1000-ml
volumetric flask and make up to the mark with
distilled water. The stock solution prepared accor-
ding to this procedure has a concentration of
1000 mg/l COD.
Further investigational concentrations may be
prepared from this stock solution by diluting
accordingly.
Stability:
When stored in a cool place (refrigerator), the
stock solution remains stable for one month.
When stored under appropriate cool conditions
(refrigerator), the diluted investigational solutions
remain stable – depending on the respective
concentration – for approximately one week to
one month.
Reagents required:
1.02400.0080 Potassium hydrogen phthalate GR
1.16754.9010 Water GR for analysis
/Kl
for analysis, volumetric standard
Release 05/04