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Identifying known unknowns using the US EPA's CompTox Chemistry Dashboard
Andrew D McEachran1, Jon R Sobus2, Antony J Williams3
1Oak Ridge Institute for Science and Education (ORISE) Research Participation Program, U.S. Environmental Protection Agency, 109 T.W. Alexander Drive, Research Triangle Park, Durham, NC, 27711, USA. mceachran.andrew@epa.gov.
Analytical and Bioanalytical Chemistry
|December 18, 2016
Summary
The U.S. EPA's CompTox Chemistry Dashboard effectively identifies unknown chemicals using mass spectrometry data. It outperforms ChemSpider by ranking chemicals with more data sources, improving exposure assessment and risk decisions.
Area of Science:
- Environmental chemistry
- Computational toxicology
- Analytical chemistry
Background:
- High-resolution mass spectrometry (HRMS) is crucial for identifying chemical features.
- Online chemical databases aid tentative identification by searching molecular formulas and masses.
- Ranking potential candidates by relevance, particularly data sources, helps identify "known unknowns".
Purpose of the Study:
- To evaluate the U.S. Environmental Protection Agency (EPA)'s CompTox Chemistry Dashboard's performance in identifying "known unknowns" compared to ChemSpider.
- To assess the utility of data source ranking for prioritizing chemical identifications.
- To demonstrate the Dashboard's potential for improving non-targeted chemical identification in environmental health science.
Main Methods:
- Evaluated the CompTox Chemistry Dashboard and ChemSpider using 162 chemicals from peer-reviewed literature.
- Performed searches using molecular formulas and monoisotopic masses for each chemical.
- Rank-ordered candidate compounds based on the number of associated references or data sources.
Main Results:
- The CompTox Chemistry Dashboard achieved a higher percentage of top-ranked chemicals compared to ChemSpider.
- Data source ranking proved advantageous for identifying "known unknowns" using the Dashboard.
- The study confirmed the Dashboard's utility for mass spectrometry-based chemical identification.
Conclusions:
- The CompTox Chemistry Dashboard offers an advantage over ChemSpider for identifying "known unknowns" through data source ranking.
- The Dashboard shows significant potential for improving non-targeted chemical identification in exposure assessment and risk decision-making.
- Further development of the Dashboard aims to enhance its non-targeted analysis workflow.