Analytical Method: Analytical Quality Assurance, Standard for COD/chloride

Reagents:
Cat.No. 102400  Potassium hydrogen phthalate for analysis, volumetric standard
Cat.No. 106406  Sodium chloride Suprapur®
Cat.No. 116754  Water for analysis
 
Preparation of a chloride dilution solution:
Dissolve 32.9 g of sodium chloride (free from organic material, e. g. Suprapur®) in a calibrated or conformity-checked 1000-ml volumetric flask and make up to the mark with distilled water. The stock solution prepared according to this procedure has a concentration of 20 g/l Cl-
 
Preparation of a COD standard solution:
Dissolve 0.851 g of potassium hydrogen phthalate in a calibrated or conformity-checked 100-ml volumetric flask and make up to the mark with dilution solution. The stock solution prepared according to this procedure has a concentration of 10 000 mg/l COD and 20 g/l Cl-. Further investigational concentrations may be prepared from this standard solution by diluting accordingly with dilution solution.
 
Stability:
When stored in a cool place (refrigerator), the dilution solution of 20 g/l Cl- and the standard solution of 10 000 mg/l COD / 20 g/l Cl- remain 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.

 

 

For use with test kits:

 

Measuring range
in mg/l COD

117058

Spectroquant® COD Cell Test for seawater / high chloride-contents

5.0 - 60.0

117059

Spectroquant® COD Cell Test for seawater / high chloride-contents

50 - 3000

 

Materials

     
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