Research Progress of Active Nitrogenous Compounds Reference Materials

Reactive nitrogenous compounds are crucial for atmospheric chemistry, and their sequestration and deposition processes will directly affect the atmospheric nitrogen cycle and the generation of secondary pollutants. Since reactive nitrogenous compounds are abundant in the atmosphere with diverse concentrations and some of them are active in nature, so the accurate measurement of reactive nitrogenous compounds is a hot and difficult issue in current research. This study summarizes the measurement techniques of typical reactive nitrogenous compounds, mainly including NO, NO₂, PAN, HONO, HNO₃, ANs and N₂O₅, and the progress of their gaseous standard gases. The study shows that mass spectrometry, spectroscopy and wet chemistry have been widely used in the in-situ measurement of various reactive nitrogenous compounds, with measurement uncertainties ranging from 4 to 30%, which require accurate standard sources for parameter calibration and routine maintenance. However, there is still an overall lack of the corresponding specifications for standard sources and parameter corrections for most reactive nitrogenous compounds, with the exception of NO_x. This study further summarizes the current development challenges and directions, and provides an outlook on the subsequent development.