Historically targeted analysis has been the only practical route to evaluate complex environmental samples. This focused testing, while effective has often missed emerging or untargeted compounds within samples. Improvements in detection & data processing capabilities of various systems have allowed scientists to more fully evaluate these same samples using non-targeted (NT) techniques. Often the evaluations are driven by a lab’s available equipment & are heavily influenced by current workflows rather than an evaluation of multiple hardware & software platforms in the hands of expert users. The EPA is currently conducting a multiple lab, multiple platform evaluation for NT analyte detection. The goal of ENTACT (EPA’s Non-Targeted Analysis Collaborative Trial) is to evaluate several platforms & strategies for analysis & reporting to facilitate future improvements to NT analysis workflows. Our previous work in this project was on the first ten blinded standard mixtures. This follow-up presentation will focus on the house dust, serum & silicone wristband samples included in the study as well as the collection of individual compound standards, which will be used to expand a high resolution, accurate mass (HRAM) library. The samples were introduced into a comprehensive two-dimensional gas chromatograph (GCxGC) coupled with a HRAM time of flight mass spectrometer (TOF-MS) in both electron ionization (EI) & chemical ionization (CI) modes. Post collection, non-target data processing software was used to find & deconvolve analytes within the samples. Deconvolved spectra were matched to existing commercial MS libraries & screened based on the peak’s retention index value, molecular ion mass accuracy & fragment ion formula fidelity. Once analysis was completed, the findings were reported to the EPA. The EPA then unblinded the samples & allowed for re-review & resubmission of results. The results of both submissions will be discussed in this presentation.

Comprehensive, non-target environmental exposome sample characterization using GCxGC and high resolution time of flight mass spectrometry

2019 Spring National Meeting

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