EPA’s OTM-45 Method for PFAS Stack Testing

The United States Environmental Protection Agency (EPA) has created a new Other Test Method (OTM) for environmental monitoring with the introduction of OTM-45, a method specifically designed for Per- and Polyfluoroalkyl Substances (PFAS) stack testing.

Background on OTM-45 and PFAS Testing

OTM-45, established by the EPA in 2021, is now the benchmark for PFAS stack testing and serves as a foundation for future testing standards in this area. This method is crucial for identifying and quantifying specific PFAS compounds in source emissions, targeting both gaseous and particulate-bound pollutants.

Five overview points on OTM-45:

1. Identification and Quantification: OTM-45 is designed to identify and determine the concentration of specific PFAS compounds in source emissions, measured in mass per unit gas volume sampled.

• Sample Collection: The method involves withdrawing gaseous and particulate-bound target pollutants from the gas stream isokinetically. These pollutants are collected in the sample probe using a glass fiber or quartz filter, a packed column of adsorbent material, and a series of impingers.

• Extraction Process: After collection, the target compounds are extracted from the individual sample collection media. The OTM-45 sampling process results in four distinct sample extract fractions for detailed analysis.

• Analysis and Quantification: The extracted samples are analyzed using Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) in the Multiple Reaction Monitoring (MRM) detection mode. Quantification of each analyte is achieved using the isotope dilution technique.

• Quality Control and Accuracy: For quality control purposes, the percent recoveries of the pre-extraction standards are calculated. The method also employs pre-sampling standards added to XAD-2 collection media before sampling, which are analyzed in the same manner as targeted PFAS compounds. This step serves as an indicator of the method’s quantitative capture efficiency. Isotopically labeled standards are used to enhance the method’s accuracy and precision.

Conclusion

The EPA’s development and implementation of OTM-45 for PFAS stack testing mark a significant advancement in environmental protection efforts. The method not only enhances our understanding of PFAS emissions but also ensures more effective regulatory compliance and environmental monitoring. Apex Instruments was able to support the EPA by providing the necessary hardware in testing OTM-45 which underscores the importance of collaborative efforts in achieving technological and environmental milestones. The EPA’s OTM-50 is currently under development for nonpolar volatile PFAS compounds using whole air canisters, and we will be updating our customers as the EPA continues to release information on this new testing method.

For further details on OTM-45 and its impact on environmental monitoring, stay tuned to our newsletter or reach out to us directly.

Reference EPA OTM-45: https://www.apexinst.com/product/pfas-sampling-system