Recent progress in chemical ionization mass spectrometry and its application in atmospheric environment

Chemical ionization mass spectrometry (CIMS) is a soft ionization technique and has become an important research tool for real-time atmospheric pollutants measurement, providing reliable datasets for elucidating the pollution formation in atmospheric environment. This review presented a summary of recent progress in development, equipment and application of CIMS in atmospheric environment, including origin of CIMS, development of ion chemistry theory in CIMS, and new hardware design of CIMS, as well as application of CIMS in monitoring of atmospheric pollutants. First, the origin and emergence of CIMS were presented through summarizing the detailed evolution history of mass spectrometry. Next, the ion chemistry theories of CIMS and their development were elaborated, including proton transfer, electron transfer, hydride abstraction, cluster or adduct ion formation and other reactions. Then, the progress of the hardware design of CIMS was focused on its ion source, drift tube and mass analyzer, and the latest equipment development was also discussed. Subsequently, on the basis of introducing the calibration method, the recent application of CIMS in the field observation and laboratory research toward atmospheric inorganic gas, volatile organics, free radicals, and aerosols were introduced. Finally, future directions and trends for CIMS were proposed to promote its efficacy in detecting atmospheric pollutants. The review provides a latest summary of CIMS development in the theory, hardware and application, facilitating a profound exploration of the potential impact of atmospheric pollutants on environment quality and human health.