Study On Calibration Method And Calibration System Of PAN Analyzer

According to the lack of calibration methods for peroxyacetyl nitrate（PAN）analyzer,a synchronous diluted photochemical synthesis system was established.The influence of various factors on the synthesis of PAN and the calibration of PAN analyzer were discussed.The optimized synthesis system could be used to achieve long-term stable synthesis of standard gaseous PAN in PAN analyzer calibration.The achievement of good linearity and repeatability of the calibration were verified.This system was used to the calibration of the PAN analyzer in the field observation of atmospheric PAN in March 2019 in Beijing.During the period,the concentration of PAN in the atmosphere ranged from 0.20×10^-9 to 7.34×10^-9,with an average value of 1.88×10^-9±1.63×10^-9.Correlation between PAN and other pollutants(O₃ and PM_2.5)during the observation period was analyzed.There was no correlation between PAN and O₃ during the observation period,while the positive correlation between PAN and PM_2.5 was proved.An automatic calibrator for PAN analyzer and the software matched with the instrument were developed based on the system built in the previous relevant studies of this paper.The instrument consists of a photochemical reaction module,a gas circuit module,a temperature module and a circuit control module.Lab VIEW was used to develop the software with the function of RS-485 serial port communication between the host computer based on PC system and various slave computers.This instrument could realize the online photochemical synthesis of standard gaseous PAN,the control of gas flow and temperature,the switch of ambient atmospheric or standard sample and other automated technologies.The reliability of the automatic calibrator was verified.It was applied to the calibration of the PAN analyzer in the field observation of atmospheric PAN in December 2019 in Beijing.The automatic calibrator and supporting software developed in this research could well implement the automatic functions missing in the current calibration of the PAN analyzer,and make up the deficiencies of the market.