To Separate Particulate and Gaseous Constituents of Atmospheric Aerosols

Secondary and oxygenated organic compounds play an important role in the atmosphere. These constituents are involved in atmospheric transformation processes, and may play a significant role in the formation of cloud condensation nuclei. Unanswered questions include the relative importance of anthropogenic and biogenic volatile organic emissions to secondary aerosol formation, as well as their global distribution and their contribution to particle growth and hygroscopicity. With current methods it is difficult to obtain time-resolved measurements of organic compounds at the compound level, especially those that are oxygenated. In situ measurements of individual species are often limited by sample size and detection limits. Proposed here is a new method relying on the physical separation of particulate constituents from most of the vapor phase based on condensationally-enhanced particle focusing and concentration. This air-to-air concentrator will enable better measurements with a variety of in-situ aerosol measurements, including the Thermal -desorption Aerosol Gas chromatograph (TAG) and particle beam mass spectrometer systems such as the Aerosol Mass Spectrometer (AMS) and the Aerosol Chemical Speciation Monitor (ACSM). Commercial Applications and Other Benefits: Answers to these questions rely on accurately measuring the concentration of a suite of specific organic compounds found in atmospheric aerosols. This will be facilitated by more accurate, and less cumbersome technology for air-to-air concentration of particulate constituents of ambient aerosols. Two types of instruments are being developed, a low flow concentrator to interface with AMS and ACSM types of instruments, and a high flow concentrator for TAG and other applications needed high-throughput concentrated particulate matter.