Ecosystems Research Division

Gasoline Composition Study

New --> Poster from 2007 National Tanks Conference (San Antonio, Texas)

Gasolines are being collected from around the U.S. to support analysis and modeling of leaking underground storage tank (LUST) sites. Samples are collected according to

• grade: regular or premium,
• proximity within a geographic location (generally three samples are collected within a geographic location),
• expected oxygenate usage: methyl-tert-butyl ether (MTBE), ethanol, none,
• a list of preferred marketers and retailers (which will remain confidential),
• elevation,
• seasons.

These samples are being collected by volunteers from 22 locales within 13 states. Included are a roughly equal number of samples from the east and west coasts, the upper mid-west, Texas and Oklahoma, and the Rocky Mountains. The samples are being analyzed for a list of chemicals that includes:

• common aromatics: benzene, toluene, ethylbenzene, xylenes (BTEX), trimethyl benzenes,
• oxygenates: methyl-tert-butyl ether (MTBE), tert-amyl methyl ether, and others,
• the forty-four chemicals included in a Canadian Petroleum Products Institute Study of 1994, and
• and other chemicals included in the "PIANO" grouping: parafins, isoparafins, aromatics, napthlenes, olefins.

The samples are also being used to determine the physical properties of the gasolines: density, viscosity and surface tension, and their partitioning among air and water.

The first samples were collected in September through November, 2004. The results from the first analysis of these data are available in an EPA report. The report presents the background and methodology of the study and three types of results:

• Comparisons of individual chemicals of interest: benzene, MTBE, tert-butyl alcohol, ethanol,
• Statistical analyses aimed at determining the similarities and differences among gasolines, and
• Predicted soil, ground water and soil gas impacts from the fuels.

Work is continuing on the analysis of samples collected in January through March 2005, further analysis of the 2004 data and the usage of the data in the EPA on-line tools for assessing subsurface contamination from petroleum hydrocarbons.

Gasoline Sampling
Samples collected by a volunteer.
Samples are shipped in a sealed shipping container under authority of 49 CFR 173.4.
Samples are logged upon receipt and placed in a 4 oC refridgerator until shipping to the laboratory.
Set of samples from a geographic location. Four replicates of two grades of gasoline are collected from three stations at a geographic location for a total of twenty-four vials.