| The circumstance of air pollution becomes sever in recent years with frequent occurrences of heavy haze,especially in beijing-tianjin-hebei,Yangtze river delta and the pearl river delta as the centers of areas.It increasingly attracts people’s widespread attention to the problems of atmospheric pollution.As a key link in the cognition,early warning,monitoring and governance of air pollution,fast and accurate analysis of atmospheric pollution components in situ has become a hot problem to solve urgently for environment and analytical science.The analysis of atmospheric sulfate and its precursor as a key part of composition analysis in atmospheric aerosols,mainly includes analyzing soluble sulfate of atmospheric particulates and the analysis of sulfur trioxide,sulfur dioxide,and so on.However,the current atmospheric analysis technology still mainly depends on the offline technology based on membrane.It is unable to realize rapid,real-time and accurate analysis of aerosols composition at this stage,severely limiting monitoring atmospheric pollution with the high temporal resolution and seriously hindering the process of control in atmospheric pollution.Therefore,development of online miniaturization device for fast and in situ analysis of sulfur-containing components in atmospheric aerosols has greatly scientific value and practical meanings.An online analysis apparatus for analyzing soluble sulfate and sulfur trioxide of atmospheric aerosols is developed by membrane-based parallel plate denuder(MPPD),particle collector(PC)and liquid waveguide capillary cell(LWCC)in a flow injection system with employing barium sulfate turbidimetry to realize online integration.Membrane-based parallel plate denuder is used for online acquiring sulphur trioxide in atmosphere.Particle collector is applied to collecting the soluble sulfate in atmospheric aerosols.The collected samples are directly analyzed with flow injection system which online cascades to liquid core waveguide and barium sulfate turbidimetry.It achieves analysis for sulphur trioxide and sulfate analysis of atmospheric aerosols.In addition,the experiment investigates analytical performance and influence of concentration of barium chloride,ethanol,glycerol,hydrochloric acid,length of reaction coil and flow rate.Meanwhile,the results indicate that the linearity range from 0.5 mg/L to 25 mg/L and detection limit of 0.086 mg/L(S/N=3)is achieved for this system,along with a precision of 4.5%in a sample volume of 20 μL under optimum conditions.When the sample volume is increasing to 200 μL,the linear range of the sulfate is about 50～1000 μg/L with precision of 3.7%and detection limit of 7.27μg/L(S/N=3).According to the corresponding mathematical calculating relationship of sulfur trioxide with sulfate,the linear range of the sulphur trioxide for this device is about 41.67～833.33 μg/L with a precision of 3.7%,the detection limit of 6.1μg/L(S/N=3)when the sample volume is 200 μL for the same conditions.The developed method has been applied to online detection of sulfate and sulfur trioxide in outdoor air.The obtained results agree well.This system can realize preliminary online analysis of sulfur components in atmospheric aerosols and has certain practical potential and value. |
