Colorimetric Determination of NO^-_2-N and NO^-_3-N in Water Samples by a Sulfanilamide Diazotation Method after Reduction with Zinc Powder

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Determination of NO^-_2-N and NO^-_3-N in water samples was achieved by using a sulfanilamide diazotation method after reduction with zinc powder. A 10 ml water sample was sufficient for colorimetric analysis. A volume of 2.5 ml of 50% CH_3COONa (pH 7.5) is adequate when NO^-_3-N is reduced with zinc powder. Nearly complete recovery of NO^-_3-N was confirmed from the overlap of calibration curves, and NO^-_3-N could be obtained from the difference between total nitrogen and NO^-_2-N. Complete decomposition of NO^-_2-N coexisting with NO^-_3-N could be carried out at pH below 3 in a boiling water bath, and remaining NO^-_3-N could be determined without interference. Copper levels higher than 0.5 ppm interfered with the determination and should be removed by treatment with ion exchange resin. By this method, as little as 0.01 ppm NO^-_2-N or NO^-_3-N in environmental water samples can be determined with good recovery.
公益社団法人日本薬学会の論文
1982-02-28