The use of non-targeted analysis (NTA) techniques to discover or monitor emerging compounds has increased substantially in recent years, however the NTA community has yet to establish minimum QA/QC practices or standard reporting criteria for publications.  Furthermore, little is known about the reproducibility of NTA across laboratories or even across methods within the same lab. To help address this issue, the U.S. EPA’s Non-Targeted Analysis Collaborative Trial (ENTACT) was initiated in 2015 and enrolled various academic, government, and industry labs to analyze mixtures of chemicals as well as environmental samples. As one component of ENTACT, participants received two standard reference material extracts of house dust (NIST SRM 2585), one of which remained unaltered and a second which was fortified with a mixture of 365 chemicals.  To investigate the chemical space covered by the extraction, clean-up, and instrumental analyses, a spiking experiment was conducted in which the chemical mixture was spiked into SRM 2585 samples at each step in the analytical procedure.  Log <i>K</i><sub>ow</sub> was a major factor contributing to compound recovery and total ion current at the time of elution was a major factor governing ion suppression when using electrospray ionization.  Furthermore, the concentration of chemicals used in this spiking experiment was lower than the levels of the pure mixture, but higher than the levels spiked into the ENTACT trial SRM 2585 sample.  This allowed us to establish limits of identification for various chemicals and compare those limits to dose estimates needed to cause toxicological effects.  Ion abundance was the most important factor for correctly identifying a chemical above elemental composition or physical-chemical properties. Instrument performance for NTA was also compared between an LC-QToF and LC-Orbitrap.  Drawing from our results, reported results from other laboratories, and discussions at the recent ENTACT 2018 workshop, recommendations for QA/QC practices and for communicating results have been made.

Using standard reference material dust and EPA’s Non-Targeted Analysis Collaborative Trial (ENTACT) mixtures to evaluate methodology and applications of NTA to environmental samples

2019 Spring National Meeting

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