Research Situation and Prospect of Gaseous Elemental Mercury Calibration Source Technology

Mercury, a toxic heavy metal and pollutant, is harmful to the ecological environment and human health. Mercury concentration is much lower than conventional atmospheric pollutants in ambient air, therefore the gaseous mercury analyzer with high-precision and ultra-low detection limit is necessary for accurate measurement. All gaseous mercury analyzers must undergo rigorous calibration and standardization procedures both prior to factory release and before operational deployment to guarantee the accuracy of instrumental test data. Due to the unique physical and chemical properties of mercury, it is extremely challenging to produce the standard gases for calibration and validation of gaseous mercury analyzers. Currently, the research and development of gaseous mercury calibration source primarily base on the stable relationship between temperature and mercury vapor pressure, including saturated mercury vapor release source and mercury vapor permeation source. This paper comprehensively and thoroughly summarizes the current status and research progress of gaseous mercury calibration source technology, analyzes the shortcomings of existing technologies, and discusses potential improvements and instrument development of future gaseous mercury calibration sources.