不同有机物对硝酸盐氮测试的影响

研究了红糖、葡萄糖、乙酸钠、甲醇、乙醇、乙酸、丙酸、丁酸、正戊酸、混合有机溶剂等10种不同有机物对麝香草酚光谱法和离子色谱法测试硝酸盐氮的影响。结果表明,溶液中含有红糖或葡萄糖时,均会对麝香草酚法测试硝酸盐氮造成影响,使得测试结果偏大;在无硝酸根离子存在时,红糖和葡萄糖的质量浓度与硝酸盐氮的测试浓度非线性相关;而乙酸钠、甲醇、乙醇、乙酸、丙酸、丁酸、正戊酸和混合有机溶剂则对麝香草酚法测试硝酸盐氮没有影响。实验发现,红糖和葡萄糖在浓硫酸的作用下与麝香草酚发生Molisch反应,形成有色复合物和红棕色不溶性沉淀。实验采用离子色谱法测试硝酸盐氮时,红糖和葡萄糖等糖类有机物对测试结果均无影响。

Effect of Different Organic Compounds on Nitrate Nitrogen Test

The effects of ten different organic compounds,brown sugar,glucose,sodium acetate,methanol,ethanol,acetate,propionate,butyrate,valerate,mixed organic solvents on the determination of nitrate nitrogen by thymol spectrophotometry method and ion chromatography method were investigated.When the solution contains brown sugar or glucose,it would affect nitrate nitrogen test by thymol spectrophotometry method,which made the test results higher than the actual values.In the absence of nitrate ions,the concentration of brown sugar and glucose were nonlinearly related to the test concentration of nitrate nitrogen;while sodium acetate,methanol,ethanol,acetate,propionate,butyrate,valerate and mixed organic solvents did not affect nitrate nitrogen test.It was found that brown sugar and glucose reacted with thymol in the presence of concentrated sulfuric acid to form colored complexes and reddish brown insoluble precipitate.When the nitrate nitrogen was tested by ion chromatography,brown sugar and glucose had no effect on the test results.