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Elemental Fluorine Detection by Dielectric Barrier Discharge Coupled to Nanoelectrospray Ionization Mass Spectrometry for Nontargeted Analysis of Fluorinated Compounds

NCJ Number
303317
Journal
Analytical Chemistry Volume: 92 Issue: 14 Dated: 2020 Pages: 10129-10137
Author(s)
K. Y. Zheng; et al
Date Published
2020
Length
9 pages
Annotation

The reported project demonstrated a novel atmospheric-pressure elemental ionization method where fluorinated compounds separated by gas chromatography (GC) were converted to Na2F+ for nontargeted detection. 

Abstract

The growing use of fluorochemicals has elevated the need for nontargeted detection of unknown fluorinated compounds and transformation products. Elemental mass spectrometry (MS) coupled to chromatography offers a facile approach for such analyses by using fluorine as an elemental tag; however, efficient ionization of fluorine has been an ongoing challenge. In the current project, the compounds were first introduced into a helium dielectric barrier discharge (DBD) for breakdown. The plasma products were subsequently ionized by interaction with a nanoelectrospray ionization (nano-ESI) plume of sodium-containing aqueous electrolytes. The studies pointed to HF as the main plasma product contributing to Na2F+ formation. Moreover, the results revealed that Na2F+ is largely formed by the ion-neutral reaction between HF and Na2A(NaA)n+, gas-phase reagent ions produced by nano-ESI where A represents the anion of the electrolyte. Near-uniform fluorine response factors were obtained for a wide range of compounds, highlighting good efficiency of HF formation by DBD regardless of the chemical structure of the compounds. Detection limits of 3.5–19.4 pg of fluorine on-column were obtained using the reported GC–DBD–nano-ESI-MS. As an example of nontargeted screening, extractions from oil-and-water-repellent fabrics were analyzed via monitoring Na2F+, resulting in detection of a fluorinated compound on a clothing item. Notably, facile switching of the ion source to atmospheric-pressure chemical ionization with the exact same chromatographic method enabled identification of the detected compound at the flagged retention time. (publisher abstract modified)

Date Published: January 1, 2020