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Cheminformatics and non-targeted analysis: A two-way street
Citation:
Ulrich, E., J. Sobus, S. Newton, Chris Grulke, A. Richard, R. Singh, A. McEachran, K. Phillips, J. Wambaugh, K. Isaacs, A. Williams, AND A. Chao. Cheminformatics and non-targeted analysis: A two-way street. 2019 Spring ACS Meeting, Orlando, Florida, March 31 - April 04, 2019.
Impact/Purpose:
Non-targeted analysis (NTA) methods use high-resolution mass spectrometry to better understand the identity of a wide variety of chemicals present in environmental samples (and other matrices). Analysis of the resultant mass spectrometry information: 1) relies on cheminformatics to identify and rank chemicals, and 2) yields data that are used by cheminformaticians and decision makers to address environmental problems. In the first case, the CompTox Chemicals Dashboard is used to propose and select chemical structures supported by mass spectrometry data, either by single substances or batch searching using accurate mass/chemical formula. In the second case, NTA experiments produce lists of chemicals detected by a specific analysis type and suspected of being present in a particular environmental matrix. Those NTA data are then used to generate models to predict a variety of useful knowledge that fills in data gaps allowing researchers and decision makers across the agency to focus on problematic (from the exposure perspective) chemicals.
Description:
NTA methods are considered a qualitative analysis type, forgoing chemical standards (often because they are not available), and producing semi-quantitative concentration data using surrogate calibration techniques. Data collection for NTA experiments focuses on being as inclusive as possible without having a preconceived notion as to what chemicals would be of interest and allows retrospective queries of the data. One source of such data is the EPA's Non-Targeted Analysis Collaborative Trial (ENTACT), which involves the blinded and unblinded analysis of nearly 1,300 unique compounds combined into ten synthetic mixtures. The wealth of information obtained from the analysis of the mixtures by at least sixteen laboratories is staggering. This information will be compiled into a publicly available database and will serve to improve our understanding of previously collected toxicity information, assist in optimizing analytical methods, and help predict the behavior of substances within the same chemical space.