Untargeted Screening of Per- and Polyfluoroalkyl Substances by HRAM-DIA Method on LCMS-9030

Significance of the Topic

The widespread occurrence of per- and polyfluoroalkyl substances (PFAS) in water, soil, food, and human tissues presents a significant analytical challenge. Traditional targeted methods quantify a limited number of known PFAS, leaving undiscovered or novel compounds undetected. An untargeted screening approach offers a comprehensive solution to identify both known and emerging PFAS in environmental samples.

Objectives and Study Overview

This study aimed to develop and validate a high-resolution accurate mass (HRAM) data-independent acquisition (DIA) method on the LCMS-9030 Q-TOF system for untargeted PFAS screening in water. Fourteen PFAS standards were used to verify sensitivity, while unknown water samples were analyzed to discover and characterize previously unreported PFAS-like species.

Methodology and Instrumentation

High-performance liquid chromatography was performed on a Shim-pack Velox C18 column with a water/ammonium acetate and acetonitrile gradient. The LCMS-9030 operated in negative electrospray ionization mode with HRAM and DIA settings covering m/z 100–1000. Samples were spiked with internal standards (13C4-PFOA and 13C4-PFOS). Data processing utilized LabSolutions Insight Explore Analyze for DIA deconvolution, mass defect filtering, formula prediction, and LabSolutions Insight Explore Assign for structural elucidation, supported by in-house and MS-DIAL PFAS libraries.

Main Results and Discussion

HRAM screening of spiked water demonstrated detection limits as low as 0.01 ng/mL for 11 PFAS and reliable quantitation up to 5 ng/mL with linear calibration (R2 > 0.94). DIA deconvolution successfully matched MS/MS spectra to library entries for all 14 standards. In unknown water samples, over 800 precursors were generated, and 16 PFAS-like features were extracted based on characteristic negative mass defects. Library searches confirmed five known PFAS, while Assign provided candidate structures for novel species, such as 2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9-hexadecafluorononanoyl fluoride.

Benefits and Practical Applications

• Comprehensive detection of both targeted and untargeted PFAS.
• High sensitivity and mass accuracy for trace-level quantitation.
• Flexible data processing workflow enabling rapid deconvolution and identification.
• Applicability to diverse water matrices for environmental monitoring and quality control.

Future Trends and Potential Applications

Advances in HRAM-DIA acquisition and machine learning-assisted spectral annotation will further enhance untargeted PFAS discovery. Integration of expanded spectral libraries and improved structural prediction tools promises broader coverage of unknown PFAS classes. Coupling this method with automated reporting pipelines may accelerate regulatory screening and risk assessment.

Conclusion

An untargeted HRAM-DIA method on the LCMS-9030 platform was successfully established and demonstrated high sensitivity for known PFAS standards. Application to real water samples yielded discovery and provisional identification of 16 PFAS-like species, illustrating the method's capability for comprehensive environmental PFAS screening.

References

1. Brahm Prakash et al., Ultra-fast LC-MS/MS analysis of PFAS in environmental samples, Shimadzu White Paper, 2019.
2. Wang Z et al., A Never-Ending Story of PFASs?, Environmental Science & Technology, 51(5), 2017, 2508–2518.
3. Liu Y et al., High-resolution mass spectrometry methods for non-target discovery and characterization of PFASs, Trends in Analytical Chemistry, 121, 2019, 115420.
4. Lee JX et al., Development of Screening Analysis Method for PFAS in Surface Water on LC-Q-TOF, Shimadzu Application News AD-0200A, 2020.
5. Koelmel JP et al., Toward Comprehensive PFAS Annotation Using FluoroMatch Software and Intelligent HR Tandem Mass Spectrometry Acquisition, Analytical Chemistry, 92(16), 2020, 11186–11194.