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Ultra-low Current Electrospray Ionization of Chloroform Solution for the Analysis of Perfluorinated Sulfonic Acids
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  • Taoqing Wang,
  • Huishan Li,
  • Nicholas Allen,
  • Ian Ferraro,
  • Anyin Li
Taoqing Wang
University of New Hampshire
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Huishan Li
University of New Hampshire
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Nicholas Allen
University of New Hampshire
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Ian Ferraro
University of New Hampshire
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Anyin Li
University of New Hampshire

Corresponding Author:[email protected]

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Rationale. Femtoamp and picoamp electrospray ionization characteristics of a non-polar solvent were explored. The direct ESI-MS analysis of chloroform extract solution enabled rapid analysis of perfluorinated sulfonic acid (PFS) analytes in drinking water. Methods. Neat chloroform solvent and extracts were directly used in a typical wire-in ESI setup using micrometer emitter tips. Ionization currents were measured with femtoamp sensitivity while ramping the spray voltage from 0 to -5000 V. Methanol was used to illustrate the characteristics of spraying chloroform. The effect of spray voltage and inlet temperature was studied. A liquid-liquid extraction workflow was developed to analyze PFOS in drinking water using an ion trap mass spectrometer. Results. The ionization onset of chloroform solution was 41 ± 17 fA at 300 V. The ionization current gradually increased with voltage while remaining below 100 pA when using voltage up to -5000 V. PFOS ion signal was significantly enhanced to improve the detection limit to 25 ppt in chloroform. Coupled with a liquid-liquid extraction workflow, detection limits of 0.38-5.1 ppt, and a quantitation range of 5-400 ppt were achieved for perfluorinated sulfonic compounds in 1 mL drinking water samples. Conclusions. Femtoamp and picoamp modes expand the solvent compatibility range of electrospray ionization and can enable quantitative analysis in ppt concentrations.
12 Dec 2022Submitted to Rapid Communications in Mass Spectrometry
13 Dec 2022Submission Checks Completed
13 Dec 2022Assigned to Editor
13 Dec 2022Review(s) Completed, Editorial Evaluation Pending
15 Dec 2022Reviewer(s) Assigned
02 Jan 2023Editorial Decision: Revise Major
13 Feb 20231st Revision Received
13 Feb 2023Submission Checks Completed
13 Feb 2023Assigned to Editor
13 Feb 2023Review(s) Completed, Editorial Evaluation Pending
14 Feb 2023Reviewer(s) Assigned
03 Mar 2023Editorial Decision: Accept