Overcoming Challenges in the Analysis of Short-Chain Per- and Polyfluoroalkyl Substances in Raw Landfill Leachates: Clean-Up Method Optimization and Interference Identification

Abstract

Landfill leachate is an important emissions hotspot for per- and polyfluoroalkyl substances (PFASs). 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 leachate by comparing different specifications of granular activated carbon (GCB) adsorbents and purification sequences. The results showed that the Envi-Carb cartridge exhibited optimal purification efficiency when applied directly to raw leachate samples, achieving recoveries for all 6 short-chain PFASs ranging from 85% to 113%, with relative standard deviations (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. 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.

Keywords: Per- and polyfluoroalkyl substances (PFASs), Clean-up method, Interference identification, Graphitized carbon black (GCB), Raw landfill leachate