AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Measurement of Semivolatile and Intermediate-Volatility Organic Compounds (S/IVOC) with a Novel Thermal Desorption Electron Impact Mass Spectrometer
JONATHAN FRANKLIN, Gabriel Isaacman-VanWertz, Jesse Kroll, MIT
Abstract Number: 527 Working Group: Aerosol Chemistry
Abstract Intermediate-volatility and semivolatile organic compounds (S/IVOCs) are believed to be key intermediates in the oxidation of large hydrocarbons and efficient precursors to secondary organic aerosol (SOA). However, a detailed understanding of the concentrations and chemical properties of these compounds in the atmosphere has been limited by a lack of fast and reliable measurements. S/IVOCs have traditionally been difficult to measure due to their low volatilities leading to losses to sampling surfaces as well as very low concentrations of individual compounds. Presented here are data collected by the Thermal Desorption- Electron Impact- Mass Spectrometer (TD-EIMS), a novel technique for the quantification and characterization of such compounds. The system cryogenically preconcentrates sample before thermally desorbing it into a high-resolution time-of-flight mass spectrometer, yielding ensemble measurements of the concentration, volatility, and chemical composition (e.g., elemental ratios) of S/IVOCs, with fast time resolution (4-6 measurements per hour). We examine an increase in oxygen content in S/IVOCs with increasing time during oxidation experiments of typical SOA precursors in the environmental chamber at MIT.