Demonstration of a Continuous, Real-Time PM2.5 Chemical Speciation Monitor Based on an Aerosol Mass Spectrometer

This Phase I research project addresses the need for improved monitoring technologies for continuous particulate mass and chemical speciation of ambient aerosols. During the last few years, Aerodyne Research, Inc., has developed an Aerosol Mass Spectrometer (AMS) instrument that measures ambient aerosol mass, chemical composition, and chemically speciated size distributions of nonrefractory submicron aerosol particles in real time. The AMS has been deployed successfully in more than 20 national and international field campaigns and has participated in several intercomparisons with a variety of independent instruments that highlight the capability of the AMS to quantitatively measure and classify particulate inorganics (ammonium, nitrate, sulfate, chloride) and organics (primary combustion, oxidized secondary compounds) in real time. The value of the AMS as a state-of-the-art aerosol research tool is underscored by its commercial success (20 instruments have been delivered to date). The goals of this SBIR Phase I research project are to develop a simpler, smaller, and cheaper autonomous prototype Aerosol Chemical Speciation Monitor (ACSM) based on the AMS and evaluate the performance of the ACSM for continuous monitoring applications by conducting side-by-side comparisons with filter measurement techniques. These goals will be accomplished through three tasks. The first task is to quantify the capability of the AMS to measure known composition laboratory PM2.5 aerosol, including supermicron and nonspherical particles. This involves the characterization of a new aerosol inlet system to increase supermicron collection efficiencies and the quantification of particle collection efficiencies using a new particle beam probe. The second task is to modify an existing AMS to test the concept of a simple, inexpensive ACSM that has the same quantitative capabilities of the original AMS. The third task is to directly compare the prototype ACSM with filter-based PM2.5 particulate mass and chemical speciation methods (Federal Reference Method and Particle Composition Method) for quantifying well-characterized laboratory-generated aerosol and ambient aerosol. In Phase II, Aerodyne Research, Inc., will build a prototype ACSM that can run autonomously for extended periods of time (without the need for expensive post-processing analyses) and deploy the system in the field. Whereas the commercial market for the existing AMS includes government and education research laboratories, the design of the proposed system will yield a simple, robust, and modestly priced aerosol chemical speciation instrument ideal for the regulatory monitoring market.