Elucidation of the last steps of photo-ammonification:analytical method development and mechanism elucidation

The mechanisms underlying the photo-ammonification of nitrogenous organic compounds(NOCs)remain unclear,partly due to the analytical challenges of small NOC intermediates.This study introduced a simple methodology for accurately and simultaneously quantifying multiple small NOCs during ammonification processes.The developed method employed phenyl isothiocyanate as derivatization reagents,followed by high-performance liquid chromatography analysis to measure primary and secondary amines,amides,as well as NH4+over variable photo-ammonification conditions.In our experimental setup,vacuum ultraviolet(VUV)irradiation serves as the controlled reaction environment to simulate harsh photo-ammonification environment.Representative NOCs,including pyridine,N,N-dimethylformamide,and acrylonitrile,were chosen due to their structural diversity and environmental relevance as model NOCs.This method was able to achieve excellent nitrogen mass balance,and revealed that the last steps of photo-ammonification involved oxidation of nitrogen-adjacent carbon to amide followed by the cleavage of N-C bond.This novel method may also help quantitative investigation of nitrogen transformations in different environmental contexts.