Spectrophotometric determination of nitrate with p-diaminodiphenylsulphone and diphenylamine-p-diaminodiphenylsulphone

p-Diaminodiphenylsulphone is used in a new spectrophotometric method for the determination of nitrate. Factors affecting the colour development are given. The useful range for a 1-cm cell is 30-300 mg l . In this range the coloured solutions are stable and obey Beer's law. The method is rapid and precise and is applicable to routine analysis of samples containing macro amounts of nitrates. For determination of micro amounts of nitrate the reagent is modified by addition of diphenylamine. The limit of determination is then 0.25 mg l at 15 degrees . This method can be considered specific for nitrate and is applicable in the presence of nitrite.