Matrix-Robust SPE LC-MS/MS Method for Short- to Long-Chain PFAS in Leachates

Per- and Polyfluoroalkyl Substances (PFAS) in the Environment
Oral Presentation

Prepared by O. Salawu, N. Ruiz, J. Borny
Lummus Technology, 13001 Bay Park RD, Pasadena, Texas, 77507, United States


Contact Information: [email protected]; 949-561-2849

ABSTRACT

Landfill leachates contain high dissolved solids and complex organic constituents that interfere with PFAS analysis by promoting solid-phase extraction (SPE) clogging, LC–MS/MS ion suppression, and biased recoveries. Few peer-reviewed studies define leachate-specific dilution/cleanup thresholds, column/mobile-phase choices, and blank controls needed to achieve stable isotope-dilution accuracy from ultrashort- to long-chain PFAS in highly suppressive industrial leachates. The main purpose of this work is to develop and demonstrate a matrix-robust, automated offline SPE LC-MS/MS method for stable isotope-dilution quantitation of ultrashort- to long-chain PFAS in leachate, aligned with EPA Method 1633A.The strategy establishes a defensible baseline using established PFAS and then tests the parameters that control performance for highly polar analytes in leachate. Sample preparation incorporates solids management, anti-clogging measures, and pre-dilution when required, and uses mixed-mode SPE selectivity (WAX/GCB-type behavior) to reduce co-extracted interferences. Chromatographic performance is evaluated through mobile-phase modifier selection (acidic versus basic regimes; volatile ammonium buffers) to balance retention and peak shape with ESI stability. Matrix effects are assessed using isotope-labeled internal standards across dilution factors and replicate industrial leachate samples. Prior leachate observations indicate that low dilution yields unstable responses and inconsistent recoveries, whereas higher dilution stabilizes recoveries across multiple PFAS classes. Overall, the workflow supports reportable performance for routine PFAS while defining operating conditions for ultrashort-chain targets, beginning with TFA, under leachate-relevant suppression and background constraints.