水質調査法における硝酸窒素の簡易分析法の検討

概要

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Simple methods for the determination of nitrate nitrogen in environmental waters were developed. To eliminate Fe (III) and Mg (II), sample water was heated for 30min with alum solution and ammonia water. After separation of the precipitate, ammonium sulfamate and hydrochloric acid were added to the solution to decompose nitrite. The pretreated sample solution was determined by the following two methods : Method A (hydrazinium sulfate reduction method), the solution was heated for 60 min at 35℃ with Cu-Zn catalysis and hydrazinium sulfate, followed by colorimetric determination of nitrite with sulfanilic acid and N-1-naphtylethlenediamine : Method B (sulfonic acid method), a solution of a sulfonic acid in concentrated sulfuric acid (a special reagent for nitrogen meter, Central Kagaku) was added to the sample solution. The violet-colored solution was measured by the nitrogen meter. The relative standard deviations with nitrate standard solutions (n=5) were 4.9% (at 0.1mg/l of nitrate nitrogen), 2.0% (0.5mg/l) and 1.8% (1.0mg/l) for method A, and 9.4% (0.1mg/l), 6.1% (0.5mg/l) and 6.0% (1.0mg/l) for method B. The analytical results of river waters around the Lake Kasumigaura (n=22) by the above two methods were in good agreement with each other with the correlation coefficient of 0.981.
1987-04-05