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Workflow and Proof of Concept for Non-Targeted Analysis of Environmental Samples by LC-MS/MS
Citation:
Rosal, C., E. Ulrich, L. McMillan, AND M. Strynar. Workflow and Proof of Concept for Non-Targeted Analysis of Environmental Samples by LC-MS/MS. Presented at 36th SETAC North America Annual Meeting, Salt Lake City, UT, November 01 - 05, 2015.
Impact/Purpose:
This is a slide presentation
Description:
The human exposure includes thousands of chemicals acquired through various routes of exposure such as inhalation, ingestion, dermal contact, and indirect ingestion. Rapid assessment and screening of these chemicals is a difficult challenge facing EPA in its mission to protect public health and the environment. A variety of methods and models to understand and predict exposures are currently in development. These tools must advance knowledge of chemicals to which we are exposed, and at what concentrations. They must also provide “ground truthing” for various high throughput exposure models. Non-targeted analysis and suspect screening are powerful techniques that have widely increased in use in recent years due to the advances in analytical instrumentation. High resolution mass spectrometry (HR-MS) coupled with liquid chromatography (LC) is the instrument of choice because of its broad applicability to many compounds and ability to detect accurate mass of both molecular ions and characteristic fragments. In the absence of such a HR-MS in a lab, we are exploring the use of LC-tandem mass spectrometry (LC-MS/MS) for non-targeted analysis to provide more evidence for confirming compound identity. A blinded 100 chemical mixture was analyzed in positive and negative electrospray ionization mode using a tiered mass spectrometry experiment approach. Initial spectral searches were conducted with LC-MS/MS libraries including NIST. Other databases available online will also be explored. Compounds identified from these experiments will be combined with LC Time of Flight accurate molecular mass determinations for high confidence chemical assignments. These combined results will then be compared to the master list of chemicals in the mixture for correct assignments. This presentation will discuss the workflow using this approach, its advantages/disadvantages and limitations, as well as the results of the experiments.