Determination of nitrate after reductive distillation

3 Determination of nitrate after reductive distillation General remarks 

Nitrate ions are reduced to ammonia by Devarda s alloy (= alloy comprising 50 % Cu, 45 % Al, 5 % Zn) in alkaline solution by means of nascent hydrogen  

The ammonia is distilled and determined by acidimetric or spectrophoto-metric means in the distillate. 

The process is suitable for determining nitrate in turbid or coloured waters or waste waters and in samples with a relatively high chlorine content (salt waters). In the case of concentrations of NO3 in excess of 

3 mg/1, final determination is by titration in the case of low concentrations, determination is by the spectrophotometric process with indophenol. 

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