Overcoming challenges in the analysis of short-chain per- and polyfluoroalkyl substances in raw landfill leachates: Clean-up method optimization and interference identification.

Municipal solid waste (MSW) landfill leachate is an important emission hotspot for per- and polyfluoroalkyl substances (PFASs) in the water environment. However, quantifying short-chain PFASs in raw landfill leachate is challenging due to severe matrix effects that occur during liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. To overcome this obstacle, an enhanced clean-up method was developed for the accurate determination of short-chain PFASs in raw landfill leachate. This method involved comparing various graphitized carbon black (GCB) adsorbents and purification sequences. The results showed that the GCB cartridge exhibited optimal purification efficiency when applied directly to raw leachate samples. It achieved recoveries for all 6 short-chain PFASs ranging from 85 % to 113 %, with RSDs ≤ 7.2 %. In particular, perfluorobutanoic acid (PFBA) and perfluoropentanoic acid (PFPeA) were most effectively separated from interfering co-extracts during chromatographic analysis, as compared to other purification strategies. Humic acid-like substances were characterized as the main components causing interference. By applying the modified method, the total concentrations of the 6 short-chain PFAS targets were found to range from 10.7 to 22.7 µg/L, representing 33.0-93.7 % of total PFASs detected. This study presents an effective approach to the extraction of short-chain PFASs from complex environmental matrices, which is important for the comprehensive determination of PFAS profiles in raw landfill leachate.