靛酚蓝分光光度法在烟叶样品总氮含量测定中的应用

采用靛酚蓝分光光度法测定烟叶中总氮含量,以探索一种测定烟叶中总氮含量的新方法。将烟叶样品用H2SO4、H2O2消化后,使烟叶中的含氮化合物全部转化为氨态氮,NH 4+在亚硝基铁氰化钠及次氯酸钠存在下,与水杨酸生成蓝绿色靛酚蓝染料,再用分光光度法定量,达到测定总氮的目的。结果表明:该法测定结果与经典半微量凯氏定氮法无显著差异,加标回收率平均可达95.61%,重现性好,精密度高,操作简便,适于大批量烟叶样品总氮的测定。

Determination of Total Nitrogen in Tobacco Leaves by Indophenol Blue Spectrophotometry

Indophenol Blue Speetrophotometry was used to determine the total nitrogen in tobacco leaves in the current work. The ohacco leaves were digested with H2SO4 and H2O2, which may convert all compounds containing nitrogen to ammonium nitrogen. Consequently, NH4＋ and salicylic acid generated blue-green indophenol blue dye with the helps of sodium nitroferricyanide and sodium hypochlorite, which can be quantified by spectrophotometry. No significant differences were obtained between the present method, with average recovery rate of 95.61% , and Kjeldahl＇ s protocol. Due to its good reproducibility, high precision and easy operation, the method is suitable for large scale determination of the total nitrogen in tobacco samples.