High-Resolution Data-Dependent Mass Spectrometry Guided by Real-Time Library Search for the Detection and Characterization of PFAS

Polyfluoroalkyl Substances (PFAS) in the Environment
Oral Presentation

Prepared by B. Bills, S. Yedla, E. George, J. Sanchez, T. Stratton, R. Tautenhahn, V. Zabrouskov
Thermo Fisher Scientific, 355 River Oaks Parkway, San Jose, CA, 95134, United States

Contact Information: [email protected]; 14089656601


PFAS comprise a category of synthetic chemicals characterized by a carbon backbone with near or complete saturation with fluorine. Valued for their hydrophobic and oleophobic traits, PFAS have been used for decades in non-stick cookware, waterproof clothing, and fire-fighting foams. These compounds resist degradation and readily bioaccumulate in plants and animals and have emerged as a prolific environmental contaminant. Characterizing these chemicals can be difficult due to the thousands of variations of the synthesized chemicals, isomeric structures, and the limited availability of reference standards.
This presentation details the use of the Real-Time Library Search feature available on the Orbitrap™ IQ-X™ Tribrid™ mass spectrometer paired with the new PFAS data processing workflow in Compound discoverer to simplify detecting and characterizing PFAS compounds. Real-Time Library Search allows the instrument to compare experimental MS2 spectra to a spectral library to generate cosine scores in real time. Compounds with scores that indicate they are likely PFAS automatically trigger additional scans, such as ddMS3, to acquire additional spectral data to aid in structure elucidation without the need for reanalysis.
In addition, a modified inclusion list allows the instrument to further focus ddMS2 data collection on compounds with a negative mass defect, a common trait of PFAS compounds. PFAS standards spiked into complex matrices are often in competition with background compounds for analytical time due to their low concentration. However, by using an inclusion list to limit ddMS2 data collection to compounds with a negative mass defect and using RTLS to trigger MS3 only on likely PFAS, the number of PFAS compounds with data dependent mass spectra in a single run can be significantly increased.
Finally, a new Compound Discoverer™ data processing workflow incorporates several data reduction techniques specifically focused on PFAS analysis to help reduce complexity and annotate fluorinated compounds.