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Analytical Method: Iron (total) in effluents

Instruments, Reagents and Accessories:

Cat.No. 173016  Spectroquant® VIS Spectrophotometer Prove 100 or

Cat.No. 173017  Spectroquant® UV/VIS Spectrophotometer Prove 300 or

Cat.No. 173018  Spectroquant® UV/VIS Spectrophotometer Prove 600 or

Cat.No. 109748  Spectroquant® Photometer NOVA 30 or

Cat.No. 109751  Spectroquant® Photometer NOVA 60 or

Cat.No. 173632  Spectroquant® Colorimeter Move 100

Cat.No. 114946  Rectangular cells 10 mm and/or

Cat.No. 114947  Rectangular cells 20 mm and/or

Cat.No. 114944  Rectangular cells 50 mm
Cat.No. 114549  Spectroquant® Iron Cell Test
Cat.No. 114761  Spectroquant® Iron Test
Cat.No. 100796  Spectroquant® Iron Test
Cat.No. 109137  Sodium hydroxide solution 1 mol/l
Cat.No. 109072  Sulfuric acid 0.5 mol/l
Cat.No. 100317  Hydrochloric acid 37 % for analysis
Cat.No. 109531  MColorpHastTM pH-indicator strips pH 0 - 6
Cat.No. 114688  Crack-Set 10C
Thermoreactor with 120 °C digestion temperature
 
alternatively to Crack-Set 10C use:
Cat.No. 114687  Crack-Set 10
Cat.No. 114724  Empty round cells incl. screw caps
 
Hints:
Sewage water containing complexing agents like EDTA or Cyanide must be digested with potassium peroxodisulfate (= K2S2O8). Digestion frees iron from these complexes. When the COD concentration is
> 300 mg/l to 500 mg/l double the quantity of potassium peroxodisulfate.
The pH of the sample must be within the range 5 - 8 before starting the digestion procedure. Adjust, if necessary, with sodium hydroxide solution or sulfuric acid.
 
Sample preparation using Crack Set 10C:

Pipette 10.0 ml pretreated sample into a digestion cell. Add 1 dose reagent R-1K (= K2S2O8), close the cell tightly, and mix. Heat the cell at 120 °C in the preheated thermoreactor for 60 min.
Allow the closed cell to cool to room temperature in the cell rack. Do not cool with cold water! Add 3 drops of reagent R-2K to the cool cell and mix. Check the pH of the solution with pH-indicator strips. Adjust the pH with sodium hydroxide solution or sulfuric acid within the range 2 - 10.
 
Sample preparation using Crack Set 10:
Pipette 10.0 ml pretreated sample into an empty cell. Add 1 drop reagent R-1 and mix. Add 1 dose reagent R-2 (= K2S2O8), close the cell tightly, and mix. Heat the cell at 120 °C in the preheated thermoreactor for 1 hour. Allow the closed cell to cool to room temperature in the cell rack. Do not cool with cold water! Add 3 drops reagent R-3 to the cool cell and mix. Check the pH of the solution with pH-indicator strips. Adjust the pH with sodium hydroxide solution or sulfuric acid within the range 2 - 10.
 
Attention:
If a brown precipitation is still available in the solution after the digestion, add 2 ml hydrochloric acid 37 % and dissolve it.
 
Transfer the now colorless solution to a 20-ml volumetric flask, adjust the pH with sodium hydroxide solution 1 mol/l to 5, fill up to the mark with water for analysis and mix well.
 
Analyse:
Determine with the above mentioned test kits
 
Calculation:
Iron (total) content in mg/l Fe = analysis value in mg/l Fe

Materials

     
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