Analytical Method: Analytical Quality Assurance, Standard for Free Chlorine (DIN)

Reagents:
Potassium iodate volumetric standard (Product No. 102404)  
Potassium iodide (Product No. 105043) for analysis 
Sulfuric acid (Product No.  109072 ) 0.5 mol/L
Sodium hydroxide solution  (Product No.  109136) 2 mol/L
Water (Product No. 116754)  for analysis
 
Preparation of a KlO₃ stock solution:
Dissolve 1.006 g of KlO₃ in 250 mL of water for analysis in a calibrated or conformity-checked 1,000-mL volumetric flask. Subsequently make up to the mark with water for analysis.
 
Preparation of a KlO₃/Kl standard solution:
Transfer 15.0 mL of the KlO₃ stock solution to a calibrated or conformity-checked 1,000-mL volumetric flask, add approx. 1 g of Kl and make up to the mark with water for analysis. 1 mL of this solution is equivalent to 0.015 mg of free chlorine.
 
Preparation of the chlorine standard solution:
Pipette 20.0 mL KlO₃/Kl standard solution into a calibrated or conformity-checked 100-mL volumetric flask, add
2 mL of H₂SO₄  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 water for analysis. The concentration of the solution is 3.00 mg/L free chlorine.
 
Stability:
The KlO₃ stock solution remains stable for 4 weeks when stored in a cool place. The KlO₃/Kl standard solution can be used for 5 hours when stored in a cool place. The dilute iodine standard solution is not stable and must be used immediately.

For use with test kits:		Measuring range in mg/L Cl2
117925	MQuantTM Chlorine Test (free chlorine)	4 - 120
117924	MQuantTM Chlorine Test (free chlorine)	25 - 500
114434	MColortestTM Chlorine Test (free chlorine)	0.01 - 0.3
111174	MColortestTM Chlorine and pH Test (free + total chlorine)	0.1 - 1.5

111157	MColortestTM Chlorine and pH Test (free + total chlorine) refill pack for 111174
111113	MColortestTM Chlorine Test Reagent Cl2-1
111114	MColortestTM Chlorine Test Reagent Cl2-2
111160	MColortestTM Chlorine and pH Test (free chlorine)	0.1 - 1.5
114670	MColortestTM Chlorine Test (free chlorine)	0.1 - 2
114978	MColortestTM Chlorine Test (free chlorine, liquid)	0.1 - 2
114979	MColortestTM Chlorine Test (free chlorine, liquid) refill pack for 114978
1.14801	MColortestTM Chlorine Test (free + total chlorine, liquid)	0.1 - 2
114803	MColortestTM Chlorine Test (free + total chlorine, liquid) refill pack for 114801
114976	MColortestTM Chlorine Test (free chlorine)	0.25 - 15
114977	MColortestTM Chlorine Test (free chlorine) refill pack for 114976
114826	MColortestTM Chlorine Test (free + total chlorine)	0.25 - 15
118326	MColortestTM Chlorine Test (free + total chlorine) refill pack for 114826
116896	Reflectoquant® Chlorine Test (free + total chlorine)	0.5 - 10.0
100595	Spectroquant® Chlorine Cell Test (free chlorine)	0.03 - 6.00
100598	Spectroquant® Chlorine Test (free chlorine)	0.010 - 6.00
100086	Spectroquant® Chlorine Reagents Cl2-1	0.010 - 6.00
100087	Spectroquant® Chlorine Reagents Cl2-2	0.010 - 6.00
119254	Spectroquant® Chlorine Powder Packs for non-Merck photometers for 10-ml-samples (free chlorine)	0 - 2.00
119256	Spectroquant® Chlorine Powder Packs for non-Merck photometers for 25-ml-samples (free chlorine)	0 - 10.00
100597	Spectroquant® Chlorine Cell Test (free + total chlorine)	0.03 - 6.00
100599	Spectroquant® Chlorine Test (free + total chlorine)	0.010 - 6.00

Materials

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