In January 2021, the EPA issued draft method OTM-45, the first air emissions test method designed specifically for per- and polyfluoroalkyl substances (PFAS). The method provides detailed guidance to testers and laboratories to measure low concentrations of multiple PFAS compounds. Numerous stationary sources have been implicated in PFAS emissions that have resulted in deposition with subsequent water and soil contamination as well as human exposure. These facilities have included a wide range of industries, such as plants manufacturing fluorinated chemicals, manufacturers who utilize PFAS compounds in coatings and other water- and stain-resistant products, metal plating, incinerators, and hazardous waste combustors. There is a significant quantity of PFAS wastes, including millions of gallons of aqueous film forming foam (AFFF), awaiting disposal. The OTM-45 method will be used as one tool to determine if and how PFAS waste can be safely disposed of or destroyed. Other air emissions sources suspected of containing PFAS compounds can now be evaluated, allowing appropriate emissions control devices to be installed to greatly limit PFAS contamination of the atmosphere and the environment.
The method is based on a similar test method (SW846 Method 0010 for semi-volatile organic compounds) with several notable changes. In the OTM-45 method, a modified Method 5 sampling train is used to collect PFAS compounds in several fractions which are analyzed separately. This train includes two sorbent cartridges utilizing XAD-2 to capture and concentrate PFAS compounds (the second cartridge serves to assess breakthrough of any PFAS collected on the first cartridge and the impingers), a filter, probe and nozzle rinse, impingers charged with highly purified water, and one impinger with silica gel. Analysis is conducted using liquid chromatography/dual mass spectrometry (LC/MS/MS).
PFAS compounds are both ubiquitous in the environment and present in many commonly used materials in stack testing and laboratory procedures. Detailed procedures are provided to minimize sample and analytical contamination by avoiding fluorine containing materials such as Teflon and utilizing specific cleaning methodologies for glassware and other materials that may contact the samples. Extensive quality assurance procedures are included to verify absence of contamination via the analysis of blanks for air sampling media, rinse solvents, and blank trains.
Quantitative Reporting Limits (QRLs) ranging from 1.5 to 2.5 nanograms (ng) per sampling train are quoted for 26 different PFAS compounds. Significantly higher QRLs were quoted for two additional PFAS compounds. Emission rate detection limits will be determined by the combination of laboratory detection capabilities and the volume of stack gas sampled. Although QRLs are provided for only 28 PFAS compounds, the method lists 50 PFAS compounds that can be detected; currently detection is limited by the availability of quantitative laboratory standards. TRC anticipates that the list of applicable analytes will expand considerably as laboratory capabilities are further developed. EPA has acknowledged that this draft method will continue to be evaluated and will evolve as testing programs are conducted and the results evaluated. In an unusual step, EPA has requested the submission of test reports from projects utilizing the method to evaluate performance.
TRC’s Air Measurement Services testing teams are well versed in the procedures incorporated in OTM-45 and immediately ready to conduct test programs using the method.
Tom Dunder, Ph.D.
Tom Dunder is Technical Director in the Air Management Services Division at TRC Companies in Raleigh, North Carolina where he performs and manages air pollutant testing programs. He has degrees in Chemistry from Columbia (A.B.), Rutgers (M.S.) and the University of North Carolina (Ph.D.). Tom has 29 years of experience in gaseous pollutant emissions measurements at a wide variety of industries (refineries, chemical plants, power plants, paper mills, etc.) with recent work in biomass/biogas processes and emerging pollutants like PFAS. Contact Tom at tdunder@trcsolutions.com.