亜鉛還元-ナフチルエチレンジアミン法における含窒素化合物の影響

概要

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In the chemical analysis for nitrogen oxides, nitrogencontaining compounds in sample gases are oxidized and absorbed in the absorption solution as NO_2- and NO_3- to give positive errors to the analytical results when the sample gases are oxidized by ozone. Recently it has been pointed out that ammonia gas remaining in the flue gases after the removal of nitrogen oxides leads to a positive error in the analytical results. In the present work we have studied the effects of ammonia and hydrogen cyanide on the chemical analysis and proposed an improved method to prevent their interferences. Nitrate ions resulting from the reaction of ammonia with ozone were about (5〜8)% of the ammonia concentration and brought about positive errors in the analysis of nitrogen oxides. These interferences could be effectively removed by using 0.0036 N sulfuric acid as absorption solution and shaking it for one minute to absorb ammonia gases prior to the reaction with ozone. About 0.2% of hydrogen cyanide gas were converted to nitrogen oxide, causing slightly positive errors. However, this interference could be eliminated by using an absorption solution of zinc sulfate and shaking that solution for one minute to increase the absorbtion-speed of hydrogen cyanide gas. In addition, it was found that less than 1000 ppm of pyridine gas do not interfere with the analytical results for nitrogen oxides.
社団法人日本分析化学会の論文
1979-03-05