Neutral Per- and Polyfluoroalkyl Substances in In Situ Landfill Gas by Thermal Desorption–Gas Chromatography–Mass Spectrometry

Abstract

Landfills receive over half of the municipal solid waste generated in the U.S. Wastes in landfills include consumer products, some of which are known to contain of per- and polyfluoroalkyl substances (PFAS). Although the occurrence of nonvolatile (ionic) PFAS in landfill leachate is established and volatile (neutral) PFAS are found in ambient air near landfills, the neutral PFAS composition of landfill gas (LFG) collected in situ from landfills is unknown. A thermal desorption–gas chromatography–mass spectrometry (TD-GC-MS) sampling and analysis approach was optimized for the quantification of 25 target neutral PFAS, including fluorotelomer alcohols (FTOHs) and five other PFAS classes, in landfill from a gas well or header pipe. Optimized LFG sampling parameters included the use of an explosion-proof pump, a 100 mL/min flow rate through a sorbent tube, and a LFG volume of 350 mL. The method was applied to LFG samples collected from southeastern U.S. landfills for method demonstration. Fluorotelomer alcohols were found at the highest levels, ranging from 830,000–4,900,000 pg/m3, which is approximately 2 orders of magnitude greater than FTOH levels reported in ambient air collected near landfills.