不同处理方法对包膜控释氮肥中氮含量检测结果的影响

Effect of Various Methods of Treatment on Test Results of Nitrogen Content of Encapsulated Controlled-Release Nitrogenous Fertilizers

针对因包膜控释氮肥样品的粒径不同而造成氮含量测定值不稳定、不准确的问题，选取同一条生产线上的5个样品作为重复，并通过缩分器直接缩分法、根据各粒径质量比缩分混合法和根据粒径不同缩分单测法3种分样方法制备粉碎样，再采用滴定法测定氮含量。通过对测定结果的分析和比较可得出：粒径在3．35～4．75mm范围内的样品质量分数占82．32％左右，且按照根据粒径不同缩分单测分样方法处理的样品所测得的氮含量值误差最小。

In connection with the problem of unstable and inaccurate test values in the determination of nitrogen content of encapsulated controlled-release nitrogenous fertilizer samples with different particle sizes, five samples from the same production line are taken for repitition, three contraction division methods are chosen for sample crushing and determination of nitrogen content by titration, and they are respectively direct contraction division, contraction division of each particle-size mass propor： tion and mixing, and contraction division of individual particle size. By analysis and comparison of the results it is found that with samples in the range of 3.35 - 4.75 mm particle sizes, the mass fraction is about 82.32%, and the third method gives a nitrogen content with the least error.