Non-targeted analysis (NTA) workflows in high-resolution mass spectrometry require mechanisms for compound identification.  One strategy for tentative identification is the use of online chemical databases such as ChemSpider.  Databases like this use molecular formulae and monoisotopic mass-based searching and rank-ordering of results by the associated number of data supplier sources, bringing the most likely candidate “known unknowns” to the top of the list.  The U.S. EPA’s iCSS CompTox Dashboard (https://comptox.epa.gov) is a highly curated and freely available resource containing more than 720,000 chemicals of relevance to environmental health science.  In this research, we evaluated the performance of the Dashboard relative to ChemSpider for the identification of “known unknowns” using 162 chemicals representing a number of previously studied datasets from peer-reviewed literature<i>. </i>Molecular formulae and monoisotopic masses were searched using both applications and ordered using their different ranking approaches.  A greater percentage of chemicals ranked in the top position when using the Dashboard and offered better overall performance for identifying “known unknowns.”  Additional data will be presented evaluating alternative sources for tentative identification of chemicals.  For example, the presence of chemicals in consumer products was incorporated into the tentative identification process and evaluated via the Dashboard.  Weight-ordering of identification ranking for inclusion into a non-targeted analysis workflow as part of the CompTox Dashboard is being developed.  <i>This abstract does not necessarily represent the views or policies of the U.S. Environmental Protection Agency.</i>

Identifying known unknowns: A comparison between ChemSpider and the US EPA’s CompTox Dashboard

253rd National Meeting (2017)

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