Citation:

Young, T., G. Black, C. Lowe, T. Anumol, J. Nunez, K. Favela, C. Fisher, Y. Feng, A. Hood, K. Peter, E. Sussman, N. Quinete, J. Sobus, W. Watson, A. Williams, AND S. Wickramesekara. Mapping Chemical Space in Non-Targeted Analysis. SETAC Focused Topic Meeting, Durham, NC, May 22 - 26, 2022. https://doi.org/10.23645/epacomptox.20126375

Impact/Purpose:

The US-EPA Center for Computational Toxicology and Exposure (CCTE) has been generating data and building software applications and web-based chemistry databases for over a decade. To support our efforts to develop new approaches to prioritize chemicals based on potential human health risks, we aggregate and curate data streams of various types to support prediction models.  Suspect, Targeted and Non-targeted Analysis mass spectrometry approaches all utilize the CompTox Chemicals Dashboard and associated meta-data streams. Advanced search capabilities supporting mass spectrometry based data analysis (all forms of targeted and non-targeted analysis) to support data required for more quantitative exposure modeling are delivered with this product. This includes mass spectral data searching of experimental versus predicted data and other advanced candidate ranking approaches. The results of these efforts will be of direct benefit to program and regional offices as well as the greater scientific community.

Description:

The methods and software tools implemented in non-targeted analysis (NTA) are numerous, allowing for highly customizable workflows with varying chemical space coverage. Predicting or defining this applicability domain for each workflow remains a challenge. An additional need therefore exists for approaches that can define the region of chemical space detectable by a selected (or planned) NTA method. Such approaches could theoretically enhance performance of NTA methods by minimizing false positives (i.e., instances when an undetectable compound is reported as being present) and increasing confidence in putative positive identificationsthat fall within the defined method applicability domain. The development of explicit chemical space mapping tools could alsogive researchers the ability to reduce the vast known chemical universe into lists of plausibly detectable and identifiable compounds.These Amenable Compound Lists (ACLs) could then be used as identification libraries and in annotation efforts as part of data processing workflows. Ultimately, understanding method boundaries will allow researchers to communicate and compare methods and results more easily, and better assess method needs on a project-byproject basis.

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