Analytical performance of single particle aerosol mass spectrometer for accurate sizing and isotopic analysis of individual particles. (15th June 2023)

• Record Type: Journal Article
• Authors: Su, Yongyang; Wei, Guanyi; Wang, Wei; Xi, Ruiyang; Wang, Xi; Xu, Jiang; Li, Zhiming
• Is Part Of: Atmospheric environment. Volume 303(2023)
• Publication Date: 2023-06-15
• Subjects: Single particle aerosol mass spectrometer -- Size -- Standard particle -- Standard solution -- Suspension -- Isotopic ratio; Air -- Pollution -- Periodicals; Air -- Pollution -- Meteorological aspects -- Periodicals; 551.51
• DOI: 10.1016/j.atmosenv.2023.119759
• Languages: English
• ISSNs: 1352-2310

Abstract

Abstract: The commercial Hexin Single particle aerosol mass spectrometer (SPAMS) has been widely used for environmental aerosol monitoring and source apportionment. However, particle size measurement is easily affected by environment pressure fluctuation and sampling orifice clogging. The capability for quantitative analysis is poor, and few isotope measurement has been reported. This paper aims to evaluate the analytical performance of SPAMS and extend its application. First, the flight time of standard particles having different densities and sizes was measured under various conditions (aerodynamic lens upstream pressure and carrier gas). We proposed a universal method for particle size calibration, measurement and correction, taking into account the effects of lens geometry (acceleration nozzle diameter), particle parameters (density, diameter, and shape factor), and operating conditions (lens upstream pressure and carrier gas). Then, isotope measurement was performed when introducing a solution droplet containing a single element. Metal oxide and metal cluster ions were observed in the mass spectrum, indicating incomplete ionization of the sample droplet. The mass discrimination effect was carefully evaluated to correct the measured isotope ratio. Results show that the achievable accuracy of the corrected isotope ratio for elements investigated was 5%. The instrumental performance was relatively poor for elements having great ionization potential or bond energy. Finally, Ag/Eu2 O3 suspension and yellow cake/ethanol suspension were analyzed for size, elemental and isotopic analysis. We confirmed that the mass discrimination effect during suspension introduction could be corrected using the mass discrimination correction factor obtained during solution introduction. The Ag, Eu and U in these suspension particles were all found to be at natural abundance. The uranium in the yellow cake was identified as sodium duranyate (Na2 U2 O7 ) with volumetric equivalent diameter of approximately 65 nm. The work presented here is beneficial for instrument improvement and wide application. Highlights: Analytical performance of a widely-used commercial Single Particle Aerosol Mass Spectrometer for accurate sizing and isotopic analysis of individual particles is evaluated. A universal method was proposed and verified for particle size calibration, measurement and correction, taking into account the effects of lens geometry, particle parameters and operating conditions. After mass discrimination correction, the accuracy of the isotope ratio for elements in individual droplets was better than 5%, which is beneficial for source identification of particulate matter. Ag/Eu2 O3 suspension and yellow cake/ethanol suspension were identified to be at natural abundance, while the uranium in the yellow cake was identified as nanosized sodium duranyate (Na2 U2 O7 ).