Analytical Method: Ammonium in effluents with high COD value

Instruments and Reagents:
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 and/or
Cat.No. 114739  Spectroquant® Ammonium Cell Test
Cat.No. 114558  Spectroquant® Ammonium Cell Test
Cat.No. 114544  Spectroquant® Ammonium Cell Test*
Cat.No. 114559  Spectroquant® Ammonium Cell Test
Cat.No. 114752  Spectroquant® Ammonium Test
Cat.No. 100683  Spectroquant® Ammonium Test
Cat.No. 100731  Sulfuric acid 95 -97 % for analysis
Cat.No. 105590  Sodium hydroxide solution 32 % for analysis
Cat.No. 107209  Hydrogen peroxide (Perhydrol®) 30 % for analysis
Cat.No. 116754  Water for analysis
*not compatible with Move 100
The decomposition with the Crack-Sets 10 or 10C (Potassium peroxodisulfate) fails with strongly organic loaded water (criteria: COD content  >300mg/l). In those cases a predecomposition to destroy the organic matrix is advisable.
Sample preparation:
Evaporate 100 ml of sample and 5 ml of sulfuric acid 95 - 97 % in a 600-ml glass beaker to about 10 ml. Mix this mixture cautiously with 5 ml Perhydrol® 30 % and heat. After the sometimes heavy reaction (gas formation, foaming) has faded, heat until SO3 - formation starts. If the solution turns brown or dark, let it cool down and add again 5 ml Perhydrol® 30 %. Once more heat until beginning SO3-formation. If the solution stays colorless or light yellow, let cool down, dilute with about 50 ml distilled water and neutralise the solution with about 14 - 15 ml sodium hydroxide solution 32 % to pH 4 - 6 using a pH - meter. After cooling transfer the solution into a 100-ml volumetric flask and fill up to volume with distilled water and mix.
Ammonium will be fixed as Ammonium sulfate in the solution and after the oxidation of the digestion can be measured with the above mentioned test kits.
Determine with the above mentioned test kits.
Ammonium content in mg/l NH4-N  =  analysis value in mg/l NH4-N


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