Fast, Accurate, and Precise: Learn how to Comply with EPA Method 325 a/b (Fenceline Monitoring for Benzene)

Oral Presentation

Prepared by L. Marotta1, R. Provost2
1 - PerkinElmer, 710 Bridgeport Avenue, Shelton, CT, 06484, United States
2 - Pace Analytical Services, 1700 Elm Street, Minneapolis, MN, 55414, United States

Contact Information:; 914-954-1779


The United States Environmental Protection Agency (EPA) has developed a new method for the passive monitoring of several volatile components in air. Benzene is the compound regulated at the fenceline of US refineries, largely because of its impact on human health. Measurements at the fenceline will determine how much benzene is possibly entering communities. There is a mandated sampling time of two weeks.

This presentation describes how to comply with the new EPA fenceline regulations, and the steps taken to optimize this method for high sample throughput and accuracy. Refineries and testing laboratories will benefit by gaining valuable information on the optimum techniques to perform this method and what it takes to comply. An introduction to the theory and operation of thermal desorption will be included.

The data from several site studies will be reviewed. These samples were collected on the same tubes used by the EPA in their development and analyzed using the same concentrator trap and automated thermal desorber. The concentration range from several sites will be discussed which will help laboratories establish proper conditions by establishing sufficient sample concentration ranges for calibration.

Method criteria including minimum detection limits (MDLs), action limits, accuracy and precision, and tuning will be demonstrated. The presentation will also discuss the prevention of false positives from other sources.