2种植株全氮测定方法比较

Comparison of Determining the Plant Total Nitrogen with Two Methods

为比较凯氏定氮和奈氏比色2种植株全氮测定方法的优劣,以20个成熟期油菜籽粒样品作为试验材料,分别用这2种方法测定全氮含量,并通过添加外源标准物质(NH4)2SO4,比较其分析准确度及精密度。结果表明:凯氏定氮法测定值略低于奈氏比色法测定值;凯氏定氮法的回收率高于奈氏比色法。凯氏定氮法回收率高,重现性好,适合准确分析少量样品或者单独测定全氮含量;奈氏比色法操作方便,准确度也能符合常规分析要求,适合大批植株样品的分析。

The determination of the plant total nitrogen has been compared with Kjeldahl method and Nessler calorimetry method.Twenty mature rapeseed samples were digested with H2SO4 and HClO4,and the sample solution of total nitrogen content was determined by the two methods, respectively.Exogenous standard substance （NH4）2SO4 was added to compare the analytical accuracy and precision.The results showed that the Kjeldahl method for the determination of value was lower than the value of the Nessler colorimetric method, and the recovery rate of the Kjeldahl method was higher than that of Nessler eolorimetry. Kjeldahl method had good reproducibility,it was suitable for accurate analysis of small amounts of sample or a separate determination of total nitrogen content, Nessler colorimetry was easy to operate, and the accuracy could meet the routine analysis requirements, it was suitable for the analysis on a large scale.