STTR Phase II: Aerosol Mass Spectrometer for Size and Composition Analysis of Sub-Micron Particles

This Small Business Technology Transfer Phase II project will develop an aerosol sampling instrument that yields both size and chemical composition information in real time for sub-micron sized particles. The instrument will have application to airborne particle analysis where commercial instrumentation is currently unavailable. The device combines proven technology for aerosol sampling and size separation with a unique hot wire particle vaporization/mass spectrometric detection scheme. This instrument is less complex compared to current research systems utilizing high power lasers for particle vaporization and, hence, will provide a significant cost reduction for particle analysis. The particle mass spectrometer combines an aerodynamic aerosol sampling inlet and charging system which generates a beam of charged particles whose size is determined by its interaction with electric fields. The mass selected beam impacts a hot wire where the particles vaporize and ionize. The resulting ions are analyzed with a molecular time of flight (TOP) mass spectrometer. The Phase I work has successfully coupled the particle mass spectrometer with the hot wire vaporization technique using quadrupole mass spectrometric detection. The initial work has demonstrated chemical composition detection for single particles for a range of liquid and solid salt particles down to 0.1 1lm diameter. The detection limit will be extended in the Phase II work to -0.03 1lm diameter. The instrument will be useful for basic atmospheric aerosol research and as a real time monitor for on-line particulate emissions from combustion sources (coal-fired power plants, and exhaust from commercial aircraft and automobiles).