Method TO-15A Determination of Volatile Organic Compounds (VOCs) in Air Collected in Specially Prepared Canisters and Analyzed by Gas Chromatography–Mass Spectrometry (GC-MS) U.S. Environmental Protection Agency Office of Research and Development National Exposure Research Laboratory Office of Air Quality Planning and Standards Air Quality Assessment Division t 2019 Method TO-15A September 2019 VOCs Acknowledgments This method was initially prepared for publication in the Compendium of Methods for the Determination of Toxic Organic Compounds in Ambient Air, Second Edition (EPA/625/R-96/010b), published in 1999. In 2014, U.S. Environmental Protection Agency (EPA) staff from the Office of the Science Advisor (OSA), the Office of Research and Development (ORD), and the Office of Air Quality Planning and Standards (OAQPS) formed a workgroup to focus on method updates. The workgroup members included Lara Phelps, Donald Whitaker, Karen Oliver, David Shelow, and Kevin Cavender. To facilitate the update of the method, the workgroup compiled a list of known needed changes to the method and also requested comments on potential method updates from the air toxics monitoring community to include the best practices and the most up-to-date instruments and procedures. EPA workgroup members considered all the comments that were received and made final decisions on how to incorporate revisions to the method. Battelle prepared an initial draft of the revised method in April 2018 under contract EP-D-13-005, WA No. 5-09. Donald Whitaker, Karen Oliver, and David Shelow prepared the draft final document, which was submitted for peer review in November 2018. Peer-review comments were incorporated by Douglas Turner and Ian MacGregor of Battelle. Donald Whitaker and Karen Oliver reviewed, revised, and prepared the final document. Authors Donald Whitaker, U.S. EPA ORD Karen Oliver, U.S. EPA ORD David Shelow, U.S. EPA OAQPS Douglas Turner, Battelle, Columbus, OH Ian MacGregor, Battelle, Columbus, OH Peer Reviewers Janice Willey, U.S. Navy, NAVSEA Laboratory Quality and Accreditation Office Doug Markle, 4D Innovations, Inc. Peter Furdyna, New York State Department of Environmental Conservation The authors wish to acknowledge the interest, comments, and conversations provided by members of the air toxics community and to recognize the original authors of Method TO-15 for initial development of the method. The authors also recognize Ingrid George, EPA ORD, for sharing data and providing thoughtful discussions and multiple reviews, Stacy Henkle of Jacobs Technology for serving as technical editor, and Stacy Henkle, Zora Drake-Richman, and Tamira Cousett of Jacobs Technology for compiling and organizing the stakeholder comments received during the updating of this method (Contract EP-C-15- 008, WAs 111 and 112). Disclaimer This method has been subjected to the Agency's peer and administrative review, and it has been approved for publication as an EPA document. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. i Method TO-15A September 2019 VOCs Contents Acknowledgments .......................................................................................................................................... i Disclaimer....................................................................................................................................................... i Acronyms and Abbreviations ...................................................................................................................... viii Units of Measure ........................................................................................................................................... x 1 Scope ...................................................................................................................................................... 1 2 Summary of Method ................................................................................................................................ 5 3 Significance ............................................................................................................................................. 6 4 Applicable Documents ............................................................................................................................ 7 4.1 EPA Documents ............................................................................................................................ 7 4.2 ASTM Standards ........................................................................................................................... 7 5 Definitions ............................................................................................................................................... 8 6 Interferences and Contamination .......................................................................................................... 10 6.1 Interferences Related to Sample Collection ............................................................................... 10 6.1.1 Leaks in the Sampling Flow Path .................................................................................. 10 6.1.2 Contaminants Entering the Flow Path ........................................................................... 10 6.1.3 Contaminants in Co-collected Samples Employing Sorbent Media–Based Methods ... 10 6.1.4 Contaminants in the Sampling Apparatus ..................................................................... 10 6.2 Canister Sampling Media Interferences ..................................................................................... 11 6.3 Analytical Interferences .............................................................................................................. 12 7 Apparatus .............................................................................................................................................. 13 7.1 Sample Container ....................................................................................................................... 13 7.1.1 Stainless-Steel Canisters ............................................................................................... 13 7.1.2 Glass Bottles .................................................................................................................. 14 7.1.3 Nonrigid Containers ....................................................................................................... 15 7.2 Canister Cleaning System .......................................................................................................... 15 7.3 Sampling Apparatus ................................................................................................................... 16 7.3.1 Grab Sampling ............................................................................................................... 16 7.3.2 Time-Integrated Sampling ............................................................................................. 16 7.3.2.1 Fixed-Site (Installed) Sampling Systems ....................................................... 17 7.3.2.2 Portable Sampling Systems .......................................................................... 17 7.3.3 Flow Control ................................................................................................................... 18 7.3.3.1 Critical Orifices .............................................................................................. 18 ii Method TO-15A September 2019 VOCs 7.3.3.2 Mechanical Flow Controlling Devices ............................................................ 18 7.3.3.3 Mass Flow Controllers ................................................................................... 20 7.4 Vacuum/Pressure Gauges .......................................................................................................... 20 7.5 Gas Regulators, Tubing, and Fittings ......................................................................................... 21 7.6 Analytical Instrumentation ........................................................................................................... 21 7.6.1 Sample Introduction ....................................................................................................... 21 7.6.2 Sample Preconcentrator ................................................................................................ 21 7.6.3 Gas Chromatographic–Mass Spectrometric System .................................................... 22 7.6.3.1 Gas Chromatograph ...................................................................................... 22 7.6.3.2 Chromatographic Column ............................................................................. 22 7.6.3.3 Mass Spectrometer ....................................................................................... 22 7.6.4 Calibration Gas Standard Preparation Equipment ........................................................ 23 7.6.4.1 Dynamic Dilution Instrumentation .................................................................. 23 7.6.4.2 Static Dilution Instrumentation ....................................................................... 24 8 Standards, Materials, and Reagents ..................................................................................................... 25 8.1 VOC Standard Stock Gas Mixtures ............................................................................................ 25 8.2 Neat Materials ............................................................................................................................