| 摘要 |
a) 0.005 to 0.05% w/v of a diphenylamine redox indicator, b) 0.1 to 2% w/v of 4,4'-sulphonyldianiline and c) 0.1 to 2% w/v of a chloride from the group comprising ammonium chloride, hydroxylamine hydrochloride or a mixture thereof are mixed with concentrated sulphuric acid and concentrated phosphoric acid or an alkaline dihydrogen phosphate. The mixed reagent is mixed with the aqueous nitrate sample to be investigated. The nitrate ions can be rapidly and simply detected, estimated or accurately determined quantitatively by observing the blue colour which forms, by comparison with standard colour samples or by colorimetry.
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