## Environmental Analysis, Chromatography, Mass Spectrometry  
### Development of an HRMS-Based Workflow to Quantify PFAs in Leadates and Urban Waters  
**L.-A. Koronaiou 1,2, C. Nannou 1,2 and D. Lambropoulou 1,2,***  
1 Laboratory of Environmental Pollution Control, Department of Chemistry, Aristotle University of Thessaloniki, GR 54124 Thessaloniki, Greece  
2 Centre for Interdisciplinary Research and Innovation (CIRI-AUTH), Balkan Center, 10 th km Thessaloniki-Thermi Rd., GR 57001 Thessaloniki, Greece  
* Correspondence: dlambro@chem.auth.gr  
Per- and polyfluoroalkyl substances (PFASs) are a diverse group of synthetic organoflu- orine compounds that have been widely used in industrial applications and consumer products such as non-stick cookware, food packaging, fire-fighting foams, carpeting, apparels, and metal plating. PFASs are persistent in the environment, bioaccumulative in wildlife and humans, and known to cause reproductive and developmental toxicity in laboratory animals and wildlife. Landfill leachate is the major pathway for PFAS to exit the municipal solid waste landfills, where their concentrations vary over time and can be much greater than those found in sanitary wastewaters. On the other hand, PFOA and PFOS are particularly poorly removed in the drinking water production chain by conventional purification processes but can be removed with active carbon filtration or by reverse osmosis. The present study comprises a comprehensive development of an analytical methodology aiming to trace and quantify a representative array of PFAs at the sub up per liter scale, also alleviating the potential sources of cross contamination. In order to achieve sufficiently low LOQs, an optimized sample pre-treatment using solid phase extraction (SPE) was conducted. Extractions from water were performed using weak anionic exchange (WAX) SPE cartridges that were tested over HLB cartridges and proved to be more efficient for a large part of the target compounds. Isotopically-labelled standardswere used for internal quantification. A high resolution (HR) Orbitrap Q Exactive Focus mass spectrometer (Thermo Fisher) equipped with a heated ESI source was used, acquiring spectra in negative ionization mode. The overall method was validated in terms of linearity, accuracy, precision, and method limits, while a matrix-effect study demonstrated that the use of matrix-matched calibration is necessary to quantify in such complex matrices with accuracy. The method yielded acceptable recoveries (70%) for the vast majority of compounds, while the LOQs were equal or lower than 10 ng/L. The application of the method in leachates as well as in WWTPs, revealed the occurrence of L-PFBS, PFHxA, and PFOA, while in WWTPs 6:2 FIS, PFOSK, and PFOA were detected. The screening capabilities of this system also allows the simultaneous or retrospective monitoring of other PFASs, as well as the suspect screening of other emerging contaminants, using the raw data files obtained by the HRMS instrument.  
This research has been co-financed by the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship and Innovation, under the call RESEARCH--CREATE--INNOVATE (2 nd Cycle) (Project acronym: PROMoTE; Project code: T2 EDK-04066).