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. 2021 Sep 22;12:5575. doi: 10.1038/s41467-021-25840-9

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© The Author(s) 2021

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

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Fig. 2 — a XLE minimizes the number of sample-processing steps for use with GC–HRMS for measurement. b Inclusion of method blanks showing similar signal level as directly injected isooctane solvent supports quality control (QC) and standard reference material (NIST SRM-1957, 1958) in each sample batch supports quality assurance (QA). Total ion intensity was calculated by the sum of intensity of all detected peaks (n = 6 independent experiments). Data are presented as average ± SEM. c XLE supports recovery of stable isotopic standards calculated as percent recovered in XLE-processed SRM-1958 (n = 16 independent experiments) as compared with unprocessed hexane and ethyl acetate mixture (n = 9 independent experiments). Red and black line: mean and median, respectively, whiskers: 10^th and 90^th percentile. d XLE is reproducible by independent operators at different analysis time. Selected chemicals that are commonly detected in human biomonitoring studies²² are presented in raw intensity (average ± SEM, n = 4 independent experiments for Operator 1, May, n = 10 for Operator 1, October and Operator 2) and illustrate comparability of results as well as long-term robustness. Pesticides are colored in purple, with polychlorinated biphenyls (PCBs) in teal, and polybrominated diphenyl ethers (PBDEs) and polybrominated biphenyl (PBB) in yellow-green. Left-to-right chemicals: 4,4′-Dichlorodiphenyldichloroethylene (DDE), PCB-138, PCB-118, hexachlorobenzene (HCB), PBDE-47, PBDE-153, and PBB-153. e Quantification of selected chemicals in SRM-1958 (average ± SEM, n = 9 independent experiments) using external standard curves (0.05–2 ng/mL in hexane and ethyl acetate mixture). Reference values of chemical mass fraction are presented by open circle (average ± SEM²⁰). Because unidentified environmental chemicals will not have recovery data, these values are expressed without correction for recovery to illustrate usefulness for untargeted analysis (e.g., compare the height of a bar to an open circle). DDD dichlorodiphenyldichloroethane, DDT dichlorodiphenyltrichloroethane, HCH hexachlorocyclohexane, OCS octachlorostyrene. f Chemical chromatography in XLE-analyzed SRM-1958 shows detection of an extensive number of environmental chemicals for quantification (peaks are color-coded by primary m/z, with chemical details in Supplementary Fig. 4). Source data are provided as a Source Data file.