Release 06/2014
Spectroquant
®
photometers NOVA 60 and Pharo photometers
Instructions for the Preparation of Standard Solutions
Standard solution of chlorine dioxide 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 13.12 ml of the KlO
3
stock solution to a calibrated or confor-
mity-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 0.025 mg of chlorine dioxide.
Preparation of the chlorine dioxide standard solution:
Pipette 20.0 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. Subsequently make
up the solution to the mark with distilled water.
The concentration of the solution is 5.00 mg/l chlorine dioxide.
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
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
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
®
Reagents required:
1.02400.0080 Potassium
hydrogen
phthalate GR
for analysis,
volum. standard
1.16754.9010 Water for
analysis
EMSURE
®
Standard solution of COD
Preparation of a standard solution:
Dissolve 0.850 g of potassium hydrogen phthalate GR with distilled
water in a calibrated or conformity-checked 1000-ml volu metric flask
and make up to the mark with distilled water.
The standard solution prepared according to this procedure has a con-
centration of 1000 mg/l COD.
Further investigational concentrations may be prepared from this stock
solution by diluting accordingly with distilled water.
Stability:
When stored in a cool place (refrigerator), the standard solution
remains stable for one month. When stored under appropriate cool
conditions (refrigerator), the diluted standard solutions (investigational
concentrations) remain stable – depending on the respective concen-
tration – for approx. one week to one month.
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