Two-Dimensional LC × DMS Analysis of 34 PFAS Compounds.

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Spectrometry

Background:

• Per- and polyfluoroalkyl substances (PFAS) are widespread environmental contaminants with potential health and ecological risks.
• Accurate quantification and identification of PFAS in environmental samples are crucial but challenging due to matrix interferences.
• Existing liquid chromatography-mass spectrometry (LC-MS) methods, while standard, face limitations in resolving all PFAS species and identifying unknowns.

Purpose of the Study:

• To evaluate the efficacy of two-dimensional (2D) separation combining liquid chromatography (LC) and differential mobility spectrometry (DMS) for PFAS analysis.
• To improve the resolution of PFAS species that coelute in one-dimensional LC.
• To assess the potential of 2D LC × DMS for identifying unknown fluorinated compounds and quantifying PFAS in real-world samples.

Main Methods:

• Analysis of 34 PFAS species using a sequential 2D LC × DMS-MS² separation scheme.
• Comparison of resolution achieved with 1D LC and 2D LC × DMS methods.
• Evaluation of limits of quantitation and feasibility for wastewater sample analysis.

Main Results:

• 2D LC × DMS achieved baseline resolution for 29 out of 34 PFAS compounds, a significant improvement over 1D LC which resolved only five.
• Targeted 2D LC × DMS-MS² analyses maintained a similar timescale to LC-MS².
• Limits of quantitation were slightly higher in 2D LC × DMS-MS² compared to LC-MS² due to ion fragmentation.

Conclusions:

• 2D LC × DMS offers enhanced separation power for complex PFAS mixtures, facilitating the identification of unknown species through distinct subclass trends.
• The method shows promise for analyzing environmental samples, successfully quantifying PFOS in wastewater, though with higher concentrations than LC-MS².
• Further development of 2D LC × DMS can advance the trace analysis of persistent organic pollutants like PFAS.