Direct Injection Screening Method for Per- and Polyfluoroalkyl Substances (PFAS) in Drinking Water Using the High Resolution Time of Flight Mass Spectrometer, the Xevo™ G3 QTof

Importance of the Topic

Per and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants with widespread industrial and consumer applications. Their resistance to degradation leads to accumulation in water sources and potential health risks. Monitoring both regulated and emerging PFAS in drinking water is critical to protect public health and comply with evolving regulations.

Objectives and Study Overview

This study evaluates a streamlined direct injection screening workflow for PFAS in drinking water using high resolution time of flight mass spectrometry. It aims to assess sensitivity, dynamic range, and the capability to detect known and unknown PFAS without extensive sample preparation.

Methodology

Water samples and PFAS standards were injected (10 µL) directly into an UPLC system modified to minimize PFAS background. Data were acquired in negative ion mode using data independent acquisition (MSE) and processed with UNIFI software. Calibration curves were generated from serial dilutions spanning 0.5 to 5000 ng/L.

Used Instrumentation

• ACQUITY Premier UPLC System with PFAS kit
• Xevo G3 QTof High Resolution Mass Spectrometer
• UNIFI Scientific Information System and waters_connect software

Main Results and Discussion

Forty-six PFAS compounds were screened, with thirty detected at limits of detection ≤5 ng/L and dynamic range exceeding three orders of magnitude. Exemplary sensitivity was demonstrated for perfluorobutanesulfonic acid (PFBS) with a detection limit of 2 ng/L and linearity up to 2000 ng/L (R2=0.99915). Direct analysis of tap, filtered, and MilliQ water identified perfluorohexanoic acid (PFHxA) in tap water at 5 ng/L with mass accuracy better than 1 ppm.

Benefits and Practical Applications

• Eliminates bias and recovery limitations of SPE by direct injection
• High mass accuracy and sensitivity enable quantification at low ng/L levels
• Allows retrospective data mining for non-target PFAS discovery
• Simplifies workflow and reduces analysis time for routine monitoring

Future Trends and Opportunities

Advances may include higher injection volumes for improved detection, integration of larger suspect and in silico libraries for de novo PFAS identification, and application of complementary structural techniques. Automation and real-time screening could further enhance throughput and data confidence.

Conclusion

The direct injection HRMS workflow on the Xevo G3 QTof provides a rapid, sensitive, and broad-spectrum approach for PFAS screening in drinking water, overcoming limitations of targeted methods and enabling detection of regulated and emerging PFAS with minimal sample preparation.

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