Chromatographic Techniques for Improving the LC/MS Quantification of PFAS

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Mass Spectrometry

Background:

• Quantifying per- and polyfluoroalkyl substances (PFAS) in complex matrices using LC/MS is challenging due to matrix interference and solvent limitations.
• Residual matrix components can interfere with MS detection, and high organic solvent content limits injection volume, hindering lower detection limits.
• Existing methods struggle to accurately quantify specific PFAS, such as perfluorobutanoic acid (PFBA), in intricate sample types like tomato extracts.

Purpose of the Study:

• To develop and validate an improved LC/MS method for sensitive and accurate PFAS quantification in complex matrices.
• To overcome challenges associated with matrix effects and solvent limitations in conventional LC/MS analyses.
• To enhance the detection and differentiation of critical PFAS compounds, including PFBA, from interfering matrix components.

Main Methods:

• A novel 'feed injection' technique was employed, introducing PFAS samples dissolved in acetonitrile at a controlled rate into the mobile phase stream.
• This technique induced an analyte focusing effect on the LC column, enabling a tenfold increase in injection volume and detection sensitivity.
• The feed injection was coupled with two-dimensional liquid chromatography (2D-LC) and triple quadrupole MS for enhanced separation and detection.

Main Results:

• The feed injection approach significantly increased injection volume and detection sensitivity for PFAS analysis.
• The 2D-LC/MS configuration effectively reduced ion suppression effects, improving overall quantification accuracy.
• This method successfully distinguished perfluorobutanoic acid (PFBA) from isomeric matrix components in tomato extracts, addressing a key analytical challenge.

Conclusions:

• The developed 2D-LC/MS approach with feed injection offers a highly effective solution for sensitive PFAS quantification in complex matrices.
• This method overcomes common analytical hurdles, including matrix interference and solvent limitations, leading to improved detection limits.
• The technique fulfills recommendations for analyzing PFBA using secondary LC separation without significantly increasing analysis time.