EVALUATION OF AUTOMATED PRESSURIZED FLUID EXTRACTION IN ACCORDANCE WITH EPA METHOD 1633A TECHNICAL REPORT Author Team Alicia Stell, Layla Abu-Al-Halaweh, Maria Swasy, Benedict Liu, Bobbie McManus CEM Corporation June 2026 Evaluation of Automated Pressurized Fluid Extraction in Accordance with EPA Method 1633A CEM Corporation Abstract This report evaluates the applicability of an automated pressurized fluid extraction (PFE) system for the solvent extraction of soil samples analyzed under the Environmental Protection Agency’s (EPA) Office of Water (OW) Method 1633, Revision A: Analysis of Per- and Polyfluoroalkyl Substances (PFAS) in Aqueous, Solid, Biosolids, and Tissue Samples by LC-MS/MS (EPA Method 1633A). To assess performance; a spiked soil, a soil certified reference material (CRM), and field-contaminated soils were processed either strictly following EPA Method 1633A or using an approach involving automated PFE in place of the manual solvent extraction procedure described in Section 11.3 of EPA Method 1633A. All sample preparation, extraction, cleanup, and LC-MS/MS analyses were outsourced to a certified laboratory. The proposed automated extraction procedure met all EPA 1633A quality criteria for spiked samples, and CRM results demonstrated all analyte recoveries within acceptance limits for both the manual and automated workflows. Additionally, PFAS results from two air-dried field-contaminated soil samples showed equivalence between the two procedures. Collectively, these findings support the use of automated PFE as a reliable alternative solvent extraction technique for soil samples analyzed under EPA Method 1633A. i Date: June 05, 2026 Evaluation of Automated Pressurized Fluid Extraction in Accordance with EPA Method 1633A CEM Corporation E.S. Executive Summary This study evaluates whether an automated pressurized fluid extraction (PFE) system can replace the manual solvent extraction procedure specified in the Environmental Protection Agency’s (EPA) Method 1633 Revision A: Analysis of Per- and Polyfluoroalkyl Substances (PFAS) in Aqueous, Solid, Biosolids, and Tissue Samples by LC-MS/MS (EPA Method 1633A) for the analysis of PFAS in soil samples. The assessment included a matrix-spiked soil, a certified reference material (CRM), and two field-contaminated soils, all processed and analyzed by a certified laboratory under full EPA Method 1633A quality-control requirements. Across all study analytes, the automated PFE approach met EPA Method 1633A performance criteria. Spiked soils extracted using PFE showed strong recoveries (mean of 101% recovery across all analytes) and low variability (mean relative standard deviation (RSD) of 4.97%) for all 40 target PFAS. CRM results met the acceptance limits for both manual and automated extractions. In field-contaminated soils, PFAS concentrations obtained by the two procedures were comparable, with PFE results within 74–112% of the manual method results with similar precision. All extracted internal standards (EIS) met method criteria. Collectively, the data demonstrates that automated PFE provides reliable and consistent extraction performance equivalent to the manual procedure. Because EPA Method 1633A is performance-based and allows alternative extraction approaches when quality criteria are met, the study supports automated PFE as an effective and compliant solvent-extraction technique for soils analyzed under EPA Method 1633A. ii Date: June 05, 2026