Improved Lower Particle Size Limit for Aerosol Time-of-Flight Mass Spectrometry

摘要

The lower detectable particle size limit for a transportable aerosol time-of-flight mass spectrometer (ATOFMS) has been im- proved to 0.08 JLm. This is lower than previously reported and has been achieved through instrumental modifications described in this paper. The uncertainty in the size measurement of parti- cles with aerodynamic diameters less than 0.18 JLm does not allow for determination of an exact size for unknown particles, but par- ticles with aerodynamic diameters as low as 0.08 JLm can still be detected and chemically analyzed. A calibration curve covering the size range 0.18-2.1 JLm is presented. Simultaneously acquired positive and negative ion mass spectra of an individual 0.08 JLm polystyrene latex sphere and an ambient particle with an aerody- namic diameter of 0.18 JLm or less obtained with a transportable ATOFMS instrument are shown. The ability to precisely size and chemically analyze particles from a polydisperse sample down to 0.18 JLm makes ATOFMS unique from other single particle mass spectrometry instruments.