Detailed Speciation and Quantification of Toxic Organic Pollutants on Particulate Matter from Diesel Engine Exhaust Emissions, 08-R9641Printer Friendly Version
Inclusive Dates: 07/01/2006 Current
Background - Fine particulate matter (PM or soot) found largely in diesel engine exhaust emissions tends to remain suspended in the air for extended periods of time. As such, it poses a great threat to human beings. Specifically, the PM10 (less than 10 micrometers PM), and more so the PM2.5 (less than 2.5 micrometers PM), can be easily inhaled by humans. The toxic chemicals adsorbed on the PM have the potential to be leached into the lung tissues, carried to various organs, where they will eventually exert their potentially deadly effects. In recent years, many studies have focused on the size and number of PM produced by the diesel engines. Although some studies have been performed concerning the speciation (identification) and quantification of the chemical species adsorbed on the PM, these studies have had limited applications. The extraction and analytical methods as well as the lack of appropriate chemical standards have made the results of previous studies doubtful at best. Under such conditions, it is difficult to assess accurately the potential hazards that PM poses to human health. Furthermore, the 2007 and 2010 diesel emission standards require additional reduction in the amount of PM allowed from the diesel-fueled on-road engines. This requirement makes the speciation and quantification of the compounds associated with PM a tremendous challenge. Good extraction, speciation, and quantification methodologies are urgently needed for current and future PM studies.
Approach - Four different extraction techniques will be used to extract the PM on Teflon coated glass fiber filters and the extraction efficiency of these methods on PM compared. The four different extraction techniques are: Soxhlet extraction, sonication, microwave extraction, and accelerated solvent extraction (ASE). Two solvents or solvent systems will be used with each extraction method. A 60-meter DB-5ms (or equivalent) gas chromatography (GC) column with 25-mm id and 25-micrometer film thickness will be used to separate the semi-volatile organic compounds (SVOCs) in the PM extracts. Hydrogen may be used as the carrier gas on the GC/MS for maximal separation of the SVOCs. Both high- and low-resolution mass spectrometers (MS) will be used along with electron impact and chemical ionization techniques. Other techniques include spectral background subtraction and a mass spectral library search will help identify unknown SVOCs. The "isotope dilution technique" will be developed to quantify identified SVOCs. Special emphasis will be placed on polycyclic aromatic hydrocarbons (PAHs), alkyl-PAHs, nitro-PAHs, oxygenates, and hopanes and steranes (biomarkers for oil contamination).
Accomplishments - No significant accomplishments have yet been made in this recently initiated project.