[Study on the method for the determination of nitric nitrogen, ammoniacal nitrogen and total nitrogen in plant].

This paper reports the determination of three nitrogen states in plants: nitric nitrogen, ammoniacal nitrogen and total nitrogen. The plant sample was digested by the Kjeldathl method with H2SO4 + H2O2. The solution of the sample was determined by three methods: absorption photometric method, indigotic colorimetry, and UV absorption photometric method after K2S2O8 oxidation. By comparing the results, the relationship among the three N states is that the total N = NH4+ + NO3-. Suitable methods were found for the determination of the elements, thus providing a scientific basis for the selection of suitable methods for chemical element analysis in plants.