Speciation of Volatile and Reacting Compounds in Particulate Matter

EPA Grant Number: R823980
Title: Speciation of Volatile and Reacting Compounds in Particulate Matter
Investigators: Johnston, Murray V. , Wexler, Anthony S.
Institution: University of Delaware
EPA Project Officer: Shapiro, Paul
Project Period: October 1, 1995 through September 30, 1998
Project Amount: $334,455
RFA: Exploratory Research - Chemistry and Physics of Air (1995) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Air , Engineering and Environmental Chemistry


In this research, two areas that are relevant to oxidation/reduction chemistry in urban and regional atmospheric aerosols will be investigated. First, a method will be developed to rapidly assess the oxidation state of chromium in single aerosol particles. Second, a method will be developed to rapidly assess the chemical composition of sulfur-containing particles (i.e., distinguish sulfates, sulfites, methanesulfonates and hydroxymethanesulfonates). The environmental impacts of chromium and sulfur are dependent upon their chemical forms - sulfates contribute to acid deposition far more than sulfites, and Cr(VI) is toxic while Cr(III) is a nutrient. In each case, individual particles will be analyzed on-line and in real-time by rapid single-particle mass spectrometry (RSMS). RSMS is a novel technique developed in our laboratory that is capable of analyzing individual particles at a rate exceeding one particle per second. The aerosol is sampled directly into a mass spectrometer where individual particles are detected by light scattering of a continuous laser beam and then ablated with a high energy pulsed laser beam. Ions produced by the ablation process are mass analyzed and a complete mass spectrum is generated for each particle. The distribution of ions in the mass spectrum is used to determine the chemical composition of the particle. Since the time between sampling and analysis is about one millisecond, chemical transformations are minimized and aerosol reactions can be studied in real-time. The methods developed in this research to speciate chromium and sulfur in single particles will be used to interpret data from field measurements and to study chemical transformations of laboratory-generated aerosols.

Publications and Presentations:

Publications have been submitted on this project: View all 29 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 12 journal articles for this project

Supplemental Keywords:

air, ambient air, atmosphere, particulates, environmental chemistry, measurement methods, Northeast, Atlantic coast, Delaware, DE, Region 3, RFA, Scientific Discipline, Air, Toxics, Geographic Area, particulate matter, air toxics, Physics, State, HAPS, Chemistry, Environmental Monitoring, Atmospheric Sciences, Engineering, Chemistry, & Physics, EPA Region, ambient aerosol, particulates, exposure and effects, Delaware (DE), acid volatile sulfide, aerosol particles, mass spectrometry, oxidation, Chromium, Region 3, air sampling, chemical composition, chemical detection techniques, sulfur, Sulfur dioxide, analytical chemistry, environmental contaminants, atmospheric aerosol particles, Chromium Compounds, urban air , atmospheric deposition, rapid single particle mass spectrometry

Progress and Final Reports:

  • 1996
  • 1997
  • Final Report