Establishing Orbitrap-Based Methods for Multi-Element Compound-Specific Isotope Analysis of Per- and Polyfluoroalkyl
Juyoung Park1,2, Linnea J Heraty3, Neil C Sturchio3
1Water Science and Policy, University of Delaware, Newark, Delaware19716, United States.
Analytical Chemistry
|July 16, 2026
Summary
Stable isotope analysis using Orbitrap mass spectrometry enables multi-element (sulfur, nitrogen, oxygen) compound-specific isotope analysis for per- and polyfluoroalkyl substances (PFAS). This advanced method enhances environmental forensics for tracing these persistent contaminants.
Area of Science:
- Environmental Chemistry
- Analytical Chemistry
- Mass Spectrometry
Background:
- Per- and polyfluoroalkyl substances (PFAS) are persistent global environmental contaminants requiring advanced identification methods.
- Stable isotope analysis is a key forensic tool for tracing contaminant origins, but multi-element characterization for PFAS is limited.
- Existing methods often focus solely on carbon isotopes, hindering comprehensive source tracking.
Purpose of the Study:
- To develop and validate a robust method for multi-element compound-specific isotope analysis (CSIA) of PFAS.
- To utilize Orbitrap mass spectrometry for simultaneous δ34S, δ15N, and δ18O measurements of PFAS.
- To assess the method's precision, accuracy, and applicability in environmental forensic investigations.
Main Methods:
- Development of a multi-element CSIA method for PFAS using Orbitrap mass spectrometry.
- Evaluation of NSO2- fragment isotopic characteristics generated via higher-energy collisional dissociation (HCD) and in-source fragmentation.
- Comparison of Orbitrap measurements with elemental analyzer-isotope ratio mass spectrometry (EA-IRMS) for δ34S, δ15N, and δ18O.
Main Results:
- High precision and accuracy were achieved for Orbitrap δ34S measurements, aligning well with EA-IRMS and resolving isotopic variations (-4.3‰ to +4.4‰).
- Simultaneous δ15N and optimized δ18O measurements showed good agreement with EA-IRMS, confirming robust multi-element capability.
- Orbitrap δ34S measurements using HCD remained stable across three orders of magnitude of perfluorobutanesulfonamide (FBSA) concentration, unlike in-source fragmentation.
Conclusions:
- The developed Orbitrap-based framework provides a high-resolution platform for multi-element isotope analysis of PFAS.
- This method offers enhanced capabilities for environmental forensics, enabling more precise tracing of PFAS sources and transformation pathways.
- The stability of HCD-generated fragment isotopes is crucial for accurate analysis across varying PFAS concentrations.
