Science Inventory

Practical Lessons Learned from the Analysis of ENTACT SRM 2585 Household Dust Extracts and Their Implications to Real World Application of NTA

Citation:

Newton, S., J. Sobus, E. Ulrich, R. Singh, A. Chao, J. McCord, S. Laughlin-Toth, AND M. Strynar. Practical Lessons Learned from the Analysis of ENTACT SRM 2585 Household Dust Extracts and Their Implications to Real World Application of NTA. 2018 ENTACT Workshop, RTP, North Carolina, August 13 - 15, 2018.

Impact/Purpose:

As part of EPA's Non-targeted Analysis Collaborative Trial (ENTACT), participants received two standard reference material extracts of house dust (SRM 2585), one of which was fortified with a mix of 365 chemicals. Analysis of the fortified dust alongside the pure standard mixture with which it was fortified provides an opportunity for each laboratory to understand their own strengths and weaknesses in applying non-targeted analysis to environmental matrices. In an initial analysis of the fortified dust, we identified (at the formula level) less than one third of the compounds identified in the pure standard mix, however, mass hits were observed for 66% of compounds. To investigate reasons for this disparity, a spiking experiment was conducted in which the mixture was spiked into SRM 2585 before and after extraction and column clean-up as well as into pure solvent to investigate matrix suppression. The concentration of chemicals used in this experiment was lower than the levels of the pure mixture but higher than the levels spiked into the ENTACT trial SRM 2585 sample. From these data, a concentration range was derived which describes the limits of identifications for a wide variety of compounds in non-targeted analysis. Furthermore, it was evident from this experiment that ion intensity was the greatest factor determining if a compound would be identified. Twenty percent of compounds were not recovered from the extraction and clean-up procedure. These compounds had significantly higher log octanol-water partitioning coefficients than compounds which were recovered. In the non-fortified dust, many of the compounds reported in literature to be present in SRM 2585 and detected via LC-ESI-MS were identified. Furthermore, two large, related features appearing to contain both chlorine and fluorine atoms, were identified. MS/MS revealed fragment masses corresponding to PFOS in one of the features and PFHxS in the other.

Description:

As part of EPA's Non-targeted Analysis Collaborative Trial (ENTACT), participants received two standard reference material extracts of house dust (SRM 2585), one of which was fortified with a mix of 365 chemicals. Analysis of the fortified dust alongside the pure standard mixture with which it was fortified provides an opportunity for each laboratory to understand their own strengths and weaknesses in applying non-targeted analysis to environmental matrices. In an initial analysis of the fortified dust, we identified (at the formula level) less than one third of the compounds identified in the pure standard mix, however, mass hits were observed for 66% of compounds. To investigate reasons for this disparity, a spiking experiment was conducted in which the mixture was spiked into SRM 2585 before and after extraction and column clean-up as well as into pure solvent to investigate matrix suppression. The concentration of chemicals used in this experiment was lower than the levels of the pure mixture but higher than the levels spiked into the ENTACT trial SRM 2585 sample. From these data, a concentration range was derived which describes the limits of identifications for a wide variety of compounds in non-targeted analysis. Furthermore, it was evident from this experiment that ion intensity was the greatest factor determining if a compound would be identified. Twenty percent of compounds were not recovered from the extraction and clean-up procedure. These compounds had significantly higher log octanol-water partitioning coefficients than compounds which were recovered. In the non-fortified dust, many of the compounds reported in literature to be present in SRM 2585 and detected via LC-ESI-MS were identified. Furthermore, two large, related features appearing to contain both chlorine and fluorine atoms, were identified. MS/MS revealed fragment masses corresponding to PFOS in one of the features and PFHxS in the other.

URLs/Downloads:

https://www.epa.gov/sciencematters/epas-entact-study-breaks-new-ground-non-targeted-research

Record Details:

Record Type: DOCUMENT (PRESENTATION/SLIDE)
Product Published Date: 08/15/2018
Record Last Revised: 02/15/2019
OMB Category: Other
Record ID: 344050

Organization:

U.S. ENVIRONMENTAL PROTECTION AGENCY

OFFICE OF RESEARCH AND DEVELOPMENT

NATIONAL EXPOSURE RESEARCH LABORATORY

EXPOSURE METHODS & MEASUREMENT DIVISION

INTERNAL EXPOSURE INDICATORS BRANCH