The method is applicable to all waters containing between 0.05 and 5 mg of nitrogen per liter or brought to this concentration by dilution. The method may be inapplicable in the presence of barium, lead, stron-tium, iodide, iodate, selenite and selenate ions, due to the formation of a precipitate. It is also inapplicable in the presence of chromium (III) ion contents greater than 20 mg/1, iron (III) ions greater than 40 mg/1 and chloride ions greater than 2 g/1.
NBN T 91-256-1977 history
1977NBN T 91-256-1977 Water analysis methods - Determination of the nitrate nitrogen -Photometric method with chromotropic acid