US EPA Announces OTM-46, an Alternative for EPA Method 23 – What Does this Mean for You?
February 22, 2022
By: Martha Maier & Bryan Vining, PhD
On February 1, 2022 the US Environmental Protection Agency (USEPA) announced new sampling and analytical methods for stationary sources – Other Test Method 46 (OTM-46) a measurement of Polychlorinated Dibenzo-p-Dioxins/Polychlorinated Dibenzofurans (Dioxins/Furans), Polychlorinated Biphenyls (PCB), and Polycyclic Aromatic Hydrocarbons (PAH). OTM-46 may be used as an alternative to EPA Method 23 as well as for regulatory information gathering under section 114 of the Clean Air Act known as Information Collection Requests (ICRs) commonly known as section 114 letters. Almost immediately after this announcement was posted, our ultratrace laboratories in North Carolina and California began to receive questions about this new method.
As with any new compliance or testing announcement, questions are raised and everyone wants to know how this will affect them. After an initial review, the similarities of OTM-46 and the proposed EPA Method 23 are obvious, and we assembled our team of experts to review, evaluate and implement OTM-46 at both of our laboratories to support stack testers and facilities across the US. Here are some of the questions and areas of interest we’ve identified:
- What does this mean for the proposed Method 23?: As you’re probably aware, we’re still awaiting the finalization of the revised EPA Method 23, however there is no date for this announcement. There are a number of Clean Air Act Information Collection Requests (ICRs) at the federal level, and since there needs to be a method referenced (and M23 was not available) OTM-46 was developed and released. As of now, this method seems only applicable to ICRs.
- What do we know about the proposed Method 23 and OTM-46?: Method 23 outlines the procedures for sampling, detection, and quantitative measurement of polychlorinated Dioxins/Furans in stack gas samples collected with probe and sampling train from stationary sources. The analytical process entails the use of high-resolution gas chromatography/high-resolution mass spectrometry on purified sample extracts. Method 23 is to be utilized to support the Clean Air Act (CAA) by cement kilns, boilers and industrial furnaces (BIF), or medical, municipal, and hazardous waste incinerators seeking compliance with Title V Permits and BIF regulations. With proposed Method 23 and OTM-46 the target analyte list of Method 23 is expanded to include PCBs and PAHs, in addition to Dioxin/Furans, from a single sampling train, as well as increasing QA/QC measurements for the laboratory by:
- Increasing the number of labeled standards – OTM-46 adds many new labeled standards, particularly for dioxins and furans. Of particular importance is the inclusion of all 17 2,3,7,8-chlorinated species as labeled standards to be spiked prior to sample extraction. In addition, new classes of standards have been added to allow a better understanding of various parts of the sample preparation process, including filter extraction efficiency, transport or transfer, and extract cleanup. PAHs feature many more 13C-labeled standards than have appeared in previous methods, such as CARB 429. These standards are more resistant to hydrogen-deuterium exchange, which means they track losses more effectively than deuterated standards.
- Standardizing reporting of detection limits and EMPCs – OTM-46 specifies the use of estimated detection limits, including the formula used to calculate them. EPA found that some laboratories were not using EDLs, and EPA desired to have all laboratories use them. The method also removes ambiguity as to the reporting of EMPCs (compounds where all identification criteria are met except for ion ratios). Previously, the reporting of these compounds as detections was optional. OTM-46 makes reporting of EMPCs required.
- Ensuring proper analyte separation – Many different GC columns can be used for the analysis of these compounds. Older columns in particular, such as the DB-5, do not offer sufficient resolution of compounds of concern (such as the 2,3,7,8-chlorinated dioxins and furans) from other compounds that are of less concern.
- Focus on results – OTM-46 allows much more flexibility in the approach to the analysis of its target compounds, which allows it to be adapted to advances in chromatography and other aspects of analysis without the method having to be revised. While allowing for more flexibility, it maintains quality and comparability of data by specifying criteria that must be met no matter what the specific details of a lab’s approach to measurement is. Thus, laboratories can improve the analysis without compromising data comparability.
- Updated storage information –The target analytes of OTM-46 are much more stable than most organic compounds of environmental concern. Dioxins and furans, in particular, are known to be very highly stable and very slow to degrade. As such, OTM-46 features updated storage and transport information for sample and extracts, allowing longer times for storage, such that storage is generally not a concern for this method, as analyses will be completed well before any hold times would impact the analysis.
- Who can perform OTM-46 laboratory analysis and when?: Enthalpy is prioritizing resources at both our ultrarace laboratories (California and North Carolina) to bring this new method on-line. In preparation for proposed EPA Method 23 many of the additional QA/QC steps have already been implemented so the effort to bring OTM-46 on-line is minimal, we anticipate both laboratories will have calibrations and validations completed by April 2022.
- What industries are predominately affected by this development?: While there are many industries affected, primary concern is for industries such as cement kilns, hazardous waste/medical and municipal incinerators, industrial boilers and furnaces, and cement/lime kilns – all looking to ensure Title V and BIF compliance.
- Is there any testing organization compliance or certification needed for this testing?: Internal validation and appropriate implementation is the only verification procedure needed. A reputable provider can answer any questions related to this level of analysis and verification.
What can I do to prepare for this?
While this development (and the impending release of M23) casts a level of uncertainty into the testing and compliance landscape, the good news is that you don’t have to go it alone. With decades of experience in program strategy and development, consulting and testing/analysis, Enthalpy is here to help you navigate these changes and ensure you are prepared for what’s coming. For additional information or to learn how you can prepare for this, please contact us here.
Meet our Experts
PFAS Program Leader
Martha is the PFAS Program Leader for Montrose Environmental and the former owner of Vista Analytical Laboratory, located in El Dorado Hills, CA. 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. She earned her BS in chemistry and philosophy at the University of Wisconsin-Madison
Meet our Experts
Bryan Vining, PhD
Bryan is the Laboratory Director for Enthalpy Ultratrace in Wilmington, NC. Bryan as over 10 years of experience as a lab director and specializes in with LC/MS/MS and isotope dilution.
He holds a PhD in chemistry from Florida State University, and he has published multiple papers and given several talks on isotope dilution assays and the assessment of measurement uncertainty in analytical assays, both isotope dilution and otherwise.