Characterization of Size Distribution and Chemical Composition of Exhaled Particles by Using Single Particle Aerosol Mass Spectrometry

KeyWord:human exhaled breath  aerosol particle  single particle mass spectrometry  size distribution  chemical composition

Abstract:

      The understanding of size distribution and chemical composition of aerosol particles in human exhaled breath could provide helpful information for disease diagnosis£¬environmental exposure assessment£¬etc.In this study£¬the feasibility for simultaneously acquiring the size distribution and chemical composition of exhaled breath particles£¨EBPs£© of human by single particle aerosol mass spectrometry£¨SPAMS£© was preliminarily investigated.The EBPs were dried with a Nafion tubing£¬then directly analyzed by SPAMS.The number concentration of EBPs for a healthy adult is about 227-1 043 pcs/L£¬and the limit of detection£¨LOD£© for obtaining a representative size distribution profile is 2 500 pieces£¬which means approximately 10 L of breath sample is required for the analysis.The exhaled particles sizes dominantly ranged from 200 nm to 1 000 nm£¬and the peak was observed at 460 nm.For the exhaled particles£¬the size distribution and chemical profiles reflect the information involving both exogenous and endogenous particles.Compared with that for particles in ambient air£¬the size distribution profile for exhaled particles contained higher abundance of relative particle numbers£¨RPNs£© in the ranges of 200-300 nm and 440-660 nm£¬which were lower than or comparable with the RPNs in the ranges of 320-420 nm and 680-2 000 nm.Regarding the chemical composition£¬it was speculated that the higher presence of CxHyO+z£¨x=1~3£¬y=1~7£¬z=1~3£©£¬PO-3£¬CN- and CNO- in the exhaled particles£¨680-2 000 nm£© might result from the endogenous phosphatidylglycerol and protein£¬whereas C-3¡¢C-4¡¢C+¡¢C+3¡¢C3H+and C+4in the range of 200-300 nm concern with the carbon of exogenous particles in the inhaled air.