Evaluation of the Measurement Performance of the Scanning Mobility Particle Sizer and Aerodynamic Particle Sizer

The performance of the Scanning Mobility Particle Sizer (SMPS, TSI Model 3934) and the Aerodynamic Particle Sizer (APS, TSI Model 3310A) were evaluated to assess their ability to obtain mass concentrations from near real-time particle number concentration measurements made as a function of particle size. Tests were performed by generating monodisperse (polystyrene latex microspheres, 0.05-9.20 mu m) and polydisperse aerosols (potassium sulfate and ammonium nitrate, mass median aerodynamic diameter (MMAD) U 0.16-0.30 mu m) and comparing mass concentrations determined by the SMPS and APS, with concentrations measured gravimetrically on Teflon filters. Previous performance evaluation tests of these instruments has focused primarily on their ability to measure particle number concentrations (Kinney et al. 1991; Wang and Flagan 1990) or mass concentrations of polydisperse aerosols with mass median aerodynamic diameters (MMAD) of about 0.7-2.5 mu m (Peters et al. 1993). Findings from the monodisperse aerosol tests indicate that the mass concentrations obtained by the APS compared similarly to those obtained using the gravimetric method for particle sizes between 0.5-9.2 mu m. Similarly, SMPS measurements were in good agreement with the gravimetric analysis for particle sizes between 0.3-0.5 mu m. However, for particles less than 0.30 mu m, the SMPS overestimated their mass concentrations by a factor of 1.5-1.6. Tests using polydisperse aerosols showed that at particle size ranges from 0.09-0.18 mu m and from 0.18-0.29 mu m, the SMPS also overestimated mass concentrations.