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On-line chloride removal from ion chromatography for trace-level analyses of phosphite and other anions by coupled IC-ICPMS
  • Abu S. Baidya,
  • Eva E. Stueeken
Abu S. Baidya
University of St Andrews
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Eva E. Stueeken
University of St Andrews

Corresponding Author:[email protected]

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Rationale: Ion chromatography combined with inductively-coupled plasma mass spectrometry is an ideal tool for measuring low concentrations of anionic species such as phosphite; however, the high concentration of chloride and other anions in natural solutions may negatively impact chromatographic separation and data quality. Method: We developed an on-line mechanism of removing chloride from the sample within the ion chromatograph, using an additional valve and a separation column that transfers chloride to waste while phosphite and most other anions are retained. We installed this system in a coupled IC-ICPMS system (ICS6000 and Element 2 in medium resolution mode) and determined linearity and detection limits. In addition, we measured phosphorous species by NMR for comparison as an alternative method for phosphite determination. Results: Chloride was fully removed from the samples while phosphite was retained and could be analysed by IC-ICPMS. Concentrations could be measured down to 0.003 µmol/L and possibly less with good linearity over the explored range (up to 1.615 µmol/L; r 2 = 0.999). In contrast, the detection limit by NMR was 6.46 µmol/L. Conclusions: The on-line removal mechanism works well for simplifying sample matrices. It removes the need for costly pre-analytical sample treatment with OnGuard columns. We confirm that IC-ICPMS is the most powerful technique for quantifying phosphite in natural solutions. The new Cl-removal method may also be applicable to analyses of other anions.
25 Aug 2023Submitted to Rapid Communications in Mass Spectrometry
25 Aug 2023Submission Checks Completed
25 Aug 2023Assigned to Editor
25 Aug 2023Review(s) Completed, Editorial Evaluation Pending
25 Aug 2023Reviewer(s) Assigned
25 Sep 2023Editorial Decision: Revise Major
09 Oct 20231st Revision Received
09 Oct 2023Submission Checks Completed
09 Oct 2023Assigned to Editor
09 Oct 2023Review(s) Completed, Editorial Evaluation Pending
09 Oct 2023Editorial Decision: Accept