Citation:

Ulrich, E., J. Sobus, Chris Grulke, A. Richard, S. Newton, M. Strynar, K. Mansouri, AND A. Williams. EPA’s non-targeted analysis collaborative trial (ENTACT): genesis, design, and initial findings. Analytical and Bioanalytical Chemistry. Springer, New York, NY, 411(4):853-866, (2019). https://doi.org/10.1007/s00216-018-1435-6

Impact/Purpose:

Non-targeted analysis (NTA) strives to detect and identify a wide range of chemicals without preconceived target list or standards. NTA methods are in their infancy, particularly as applied to human and ecological exposures, with uncertainties regarding quality control and domain of applicability. Studies are therefore needed to define performance benchmarks so that NTA data are better understood and appropriately used in exposomic investigations. EPA's Non-Targeted Analysis Collaborative Trial (ENTACT) partnered with about 30 laboratories worldwide to evaluate the same sixteen samples to better understand the current capabilities, strengths and weaknesses of NTA. This manuscript describes ENTACT, preparation of the samples, and information shared with participating laboratories. This article is the primary point-of-reference for subsequent examinations of ENTACT data, and the foundation for all methods, data, and guidance that emerge from future analyses.

Description:

In August 2015, the US Environmental Protection Agency (EPA) convened a workshop entitled “Advancing non-targeted analyses of xenobiotic chemicals in environmental and biological media.” The purpose of the workshop was to bring together the foremost experts in non-targeted analysis (NTA) to discuss the state-of-the-science for generating, interpreting, and exchanging NTA measurement data. During the workshop, participants discussed potential designs for a collaborative project that would use EPA resources, including the ToxCast library of chemical substances, the DSSTox database, and the CompTox Chemicals Dashboard, to evaluate cutting-edge NTA methods. That discussion was the genesis of EPA’s Non-Targeted Analysis Collaborative Trial (ENTACT). Nearly 30 laboratories have enrolled in ENTACT and used a variety of chromatography, mass spectrometry, and data processing approaches to characterize ten synthetic chemical mixtures, three standardized media (human serum, house dust, and silicone band) extracts, and thousands of individual substances. Initial results show that nearly all participants have detected and reported more compounds in the mixtures than were intentionally added, with large inter-lab variability in the number of reported compounds. A comparison of gas and liquid chromatography results shows that the majority (45.3%) of correctly identified compounds were detected by only one method and 15.4% of compounds were not identified. Finally, a limited set of true positive identifications indicates substantial differences in observable chemical space when employing disparate separation and ionization techniques as part of NTA workflows. This article describes the genesis of ENTACT, all study methods and materials, and an analysis of results submitted to date.

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