What is OTM-45?

June 2, 2023

By: Blake Ericson, Martha Maier, and Bryan Vining

What is OTM-45?

In 2021, as part of their larger effort to target and address PFAS, the EPA introduced Other Test Method 45 (OTM-45) a performance-based method applicable to the collection and quantitative analysis of specific semi-volatile and particulate-bound per- and polyfluoroalkyl substances (PFAS) in air emissions from stationary sources.

While the EPA continues to gather information and refine its PFAS response and strategy, OTM-45 provides a solid starting point for organizations conscious of the impacts of PFAS and the importance of getting on the front end of the reporting and mitigation chain.

How is OTM-45 used?

Montrose has been at the forefront of the OTM-45 stack testing method since day one. Here are some basics about this method. OTM-45:

  • Collects gaseous and particulate-bound target pollutants
  • Withdraws samples from the gas stream isokinetically
  • Collects samples in a probe with a glass or quartz filter, on a packed column of absorbent material, and in a series of impingers
  • Delivers results in 4 discreet sample extract fractions for analysis
  • Produces extracts for analysis by LC-MS/MS at an experienced lab

Since this method is the EPA’s initial tool to gather information and aid in decision-making, it’s important to note that this is a starting point. It is not a regulatory or compliance method or final word on PFAS measurement in air emissions.

With this method still in its infancy, cleanups are relatively few and not very effective, and the XAD has significant PFAS background, resulting in elevated detection limits for some compounds.  But there is still much to be learned from this method.

Are there any downsides to OTM-45?

This method is still evolving, but some things to be aware of include:

  • Every train ends up being four samples, and with the depth of EPA quality control in this method, there is a premium price for this testing.
  • With four extractions per train, turnaround times may be longer.
  • Plan to spend some time reviewing the data.

What’s Next?

In this blog we’ve briefly covered what OTM-45 is, and some of the expectations of using this method. If you’re interested in talking with an expert about this method, please reach out.

Blake Ericson
Business Development Manager
Blake’s primary focus is promoting FTIR and FTIR-related technologies in source testing and ambient/fence-line sampling. Mr. Ericson has over a decade of experience in the fields of air quality management, engineering, and regulatory testing; primarily involving FTIR and GC-FTIR technologies. He began as a chemist and analyst for Prism Analytical Technologies in February 2015. Since then he has completed >150 individual projects both solo and with teams throughout the United States and internationally. Mr. Ericson received his MBA and BS in Biochemistry from Central Michigan University.

Martha Maier, PhD
PFAS Program Leader
Martha heads the expansive and innovative PFAS Program at Montrose. Formerly the President and Laboratory Director of Vista Analytical Laboratory, located in El Dorado Hills, CA, Martha has been at the forefront of PFAS analysis since Vista developed their in-house analytical method for serum in 2007. She is a member of the ITRC PFAS Committee, as well as the Sampling and Analysis Subcommittee. Before Vista was acquired by Montrose in 2021, she had been the Laboratory Director at Vista since 2002 before becoming the majority owner in 2011. Martha earned her BS in chemistry and philosophy at the University of Wisconsin-Madison. She has over 30 years of experience in environmental chemistry, primarily involving high resolution mass spectrometry for the analysis of chemicals such as dioxins, PCBs and chlorinated pesticides.

Bryan Vining, PhD
Lab Director
Dr. Bryan Vining is the Laboratory Director for Enthalpy Analytical Ultratrace in Wilmington, N.C. where he has led the team for 6+ years. He started his career in the pharmaceutical sector where he developed an expertise in LC/MS/MS and isotope dilution. He then served as the Laboratory Director for a large environmental testing company for 8 years before joining Enthalpy Analytical. Dr. Vining holds a Ph.D. in chemistry from Florida State University and has authored, published, and presented multiple scientific papers on isotope dilution methodology at industry conferences and meetings. Dr. Vining has championed collaborative efforts to develop tools for quantifying and understanding measurement certainty for isotope dilution assays and has considerable expertise in the analysis of environmental contaminants at ultratrace levels in air, soil, and water.

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