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Using High Resolution Mass Spectrometry (HRMS) to Discover Unknown Chemicals in Environmental Samples
Citation:
Strynar, M. Using High Resolution Mass Spectrometry (HRMS) to Discover Unknown Chemicals in Environmental Samples. 2021 ASA, CSSA, SSSA INTERNATIONAL ANNUAL MEETING, Salt Lake City, UT, November 07 - 10, 2021.
Impact/Purpose:
Invited presentation to help the conference attendees understand the importance of non-targeted analysis (NTA) and the use of high resolution mass spectrometry (HRMS) in environmental studies.
Description:
Targeted analysis methods for chemicals in environmental media are the backbone of monitoring studies. These methods are highly multi-laboratory validated and time-tested approaches for a host of environmental studies. However, there are shortcomings to this approach. The chosen methods only monitor for a select set of analytes. High resolution mass spectrometry (HRMS) instrumentation (e.g. QTOF and Orbitrap) partially fills this void by allowing the analysis of chemicals without any preconceived notion of what is in the sample being analyzed. This is done often through two approaches: 1) suspect screening – screening for chemicals in a large list 2) non-targeted screening – true novel compound discovery and structure elucidation. This approach is not without its own deficiencies as well. The selected extraction techniques and instrument used (e.g. GC vs LC) bias the possible detected analytes and is not comprehensive. Additional challenges include generally more expensive instrumentation, more laborious data processing/mining techniques, extremely large data sets and often a lack of chemical standards for compound confirmation and quantitation. An added benefit of HRMS analysis is data banking of previously run samples that can be mined in future efforts to explore chemicals that were either unknown at the time of analysis or were overlooked. Non-targeted methods should inform analysts about what chemicals should be added to targeted analysis methods, not take the place of them. This talk will present approaches used in the discovery of xenobiotic chemicals in environmental media using HRMS application.
