Citation:

McEachran, A., A. Chao, H. Al-Ghoul, C. Lowe, Chris Grulke, J. Sobus, AND A. Williams. Revisiting Five Years of CASMI Contests with EPA Identification Tools. Metabolites. MDPI, Basel, Switzerland, 10(6):260, (2020). https://doi.org/10.3390/metabo10060260

Impact/Purpose:

Non-targeted analysis (NTA) strives to detect and identify a wide range of chemicals without preconceived target list or standards. Such efforts can be applied to and use a variety of exposure science efforts, including basic research into the technique (ENTACT), informatics tools (CompTox Chemicals Dashboard), complex mixtures (UVCBs) and pairing exposure to effects (EDA). Approximately 30 laboratories worldwide are characterizing their non-targeted analysis approaches. Because the instrumental and data processing methods vary significantly, so do performance metrics. Physicochemical properties are statistically different between instrumental method choices (gas vs. liquid chromatography, electrospray vs. atmospheric pressure chemical ionization) showing the techniques cover different portions of chemical space. Current and future NTA research areas are also linked to larger scientific efforts within the exposure community at EPA.

Description:

Software applications for high resolution mass spectrometry (HRMS)-based non-targeted analysis (NTA) continue to enhance chemical identification capabilities. Given the variety of available applications, determining the most fit-for-purpose tools and workflows can be difficult. The Critical Assessment of Small Molecules (CASMI) contests were initiated in 2012 to provide a means to evaluate compound identification tools on a standardized set of blinded MS/MS data. Five CASMI contests have resulted in recommendations, publications, and invaluable datasets for practitioners of HRMS-based screening studies. The US EPA’s CompTox Chemicals Dashboard is now recognized as a valuable resource for compound identification in NTA studies. Yet, this application was too new and immature in functionality to participate in the 5 previous CASMI contests. In this work, we performed compound identification on all 5 CASMI contest datasets using Dashboard tools and data in order to critically evaluate Dashboard performance relative to that of other applications. CASMI data was accessed via http://casmi-contest.org/ and processed for use in our spectral matching and identification workflow. Relative to applications used by former contest participants, our tools, data, and workflow performed well, placing more challenge compounds in the top 5 of ranked candidates than did the winners of three contest years and tying in a fourth. In addition, we conducted an in-depth review of the CASMI structure sets and made these reviewed sets available via the Dashboard. Our results suggest that Dashboard data and tools would enhance chemical identification capabilities for practitioners of HRMS-based NTA.

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