Optimization and Validation of Methodology for the Organic Chemical Characterization of Particulate MatterEPA Grant Number: U916003
Title: Optimization and Validation of Methodology for the Organic Chemical Characterization of Particulate Matter
Investigators: Alvarez-Aviles, Olga
Institution: University of Puerto Rico, Central Administration
EPA Project Officer: Graham, Karen
Project Period: January 1, 2001 through January 1, 2004
Project Amount: $72,840
RFA: Minority Academic Institutions (MAI) Fellowships for Graduate Environmental Study (2001) RFA Text | Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Academic Fellowships , Fellowship - Environmental Science
Particulate matter (PM) is among the common air pollutants that are studied by environmental scientists and regulated by government agencies. The U.S. Environmental Protection Agency regulates particles that are 10 microns or less in size. Since the standards were revised in 1987, many important new studies have been published showing that breathing PM at concentrations allowed by the PM standard for 10-micron particles can cause significant health effects.1 Also, it has been shown that particles can influence the global climate by scattering sunlight and by serving as cloud condensation nuclei, which lead to lower earth temperatures.2 Among the possible causal agents for PM effects may be particle mass concentration, particle number concentration, acid aerosols, and chemical composition of particles.3,4,5,6 These characteristics of PM and their effects typically vary with time, sources, and meteorological conditions, as well as within regions.4,6 Because of these effects, it is critical to understand the sources, formation processes, fate, and physical and chemical properties of air particles. The objective of this research project is to increase the scope of organic compounds that can be identified in PM by pursuing a methodology that will allow characterization of fine aerosols with smaller sample volumes.
The approach in recent years of studies of PM has been on its chemical composition. This is because of the identification of known toxic compounds as components of the PM and because many of the physical properties also will depend on this composition. Most of the existing methodology requires sampling large volumes of air or the composite of samples to accumulate enough particles, which as consequence accent artifacts phenomena because of the long sampling time, and the giving up of detailed composition and size data. This is why an analytical methodology that allows working with small quantities and low concentration samples is needed, giving more reliability to the composition and source apportionment results.
The greater preconcentration and sample-introduction techniques of stir bar sorptive extraction and thermal desorption coupled to gas chromatography/mass spectrometry (GC/MS) have been proven effective in other fields. This will minimize artifact formation and provide a more reliable characterization. Besides these improvements to optimize the GC/MS analysis of organics, liquid chromatography with spectroscopic or mass spectrometry detectors have always been a better separation alternative for the larger, less volatile and highly polar compounds. These techniques have advantages and disadvantages, but in combination, they are a powerful approach to achieve a more complete characterization of the organic compounds in PM that can be related to its climatologic and toxicological effects.
1. EPA Region 2 – The Region of Diversity: State of the Environmental 1998: Air Quality.
2. Harrison RM, van Grieken RE. Atmospheric particles. New York, NY: Jon Wiley & Sons, Inc., 1998, pp. 1-28.
3. Reyes DR, Rosario O, Rodríguez JF, Jiménez BD. Toxic evaluation of organic extracts from airborne particulate matter in Puerto Rico. Environmental Health Perspectives 2000;108(7):635-640.
4. Tsai FC, Apte MG, Daiey JM. An exploratory analysis of the relationship between mortality and the chemical composition of airborne particulate matter. Inhalation Toxicology 2000;12(Suppl 2):121-135.
5. Brunekreef B. Session 2: What properties of particulate matter are responsible for health effects? Inhalation Toxicology 2000;12(Suppl 1):15-18.
6. Samet JM. What properties of particulate matter are responsible for health effects? Inhalation Toxicology 2000;12(Suppl 1):19-21.