SPE Phase Extraction Comparison for PFAS Compounds

Polyfluoroalkyl Substances (PFAS) in the Environment
Oral Presentation

Prepared by R. Jack, S. Lodge, S. Huq
Phenomenex, 86 Lester ave, San Jose, California, 95125, United States


Contact Information: richardj@phenomenex.com; 408-242-2996


ABSTRACT

The use of solid phase extraction has been validated for the extraction of PFAS in drinking water by EPA methods 537.1 and 533. EPA 537.1 procedure uses a 250-mL water sample fortified with surrogates and passed through an SPE cartridge containing polystyrenedivinylbenzene (SDVB) to extract the method analytes and surrogates. The compounds are eluted from the solid phase sorbent with a small amount of methanol. By contrast, EPA 533 uses a 100–250 mL sample fortified with isotopically labeled analogues of the method analytes that function as isotope dilution standards. The sample is passed through an SPE cartridge containing polystyrene divinylbenzene with a positively charged diamino ligand to extract the method analytes and isotope dilution analogues. The cartridge is rinsed with sequential washes of aqueous ammonium acetate followed by methanol, then the compounds are eluted from the solid phase sorbent with methanol containing ammonium hydroxide. The US department of defense has developed a Quality systems manual which recommends the use of an SPE with a weak anion exchange followed by a cleanup step using graphitized carbon for non-potable waters, and soils.
PFAS compounds are not all the same and include differences in carbon length and additional functionality. For example, PFAS compounds include PFCA’s from C4-C18, PFSA’s from C4-C10, Perfluorooctane Sulfonamide and Derivatives (PFOSA, FOSEs, FOSAs, and FOSAAs), Fluorotelomer sulfonates(FTS) , Fluorotelomer carboxylic acids(FTCA), Perfluoroalkyl ether carboxylic acids (PFECA), Chlorinated Polyfluoroalkyl Ether Sulfonic Acids (Cl-PFESAs) plus four additional compounds Nonafluoro-3,6-dioxaheptanoic acid (NFDHA), Perfluoro(2-ethoxyethane) sulfonic acid (PFEESA), Perfluoro-3-methoxypropanoic acid (PFMPA), Perfluoro-4-methoxybutanoic acid (PFMBA).
This talk will present a comparison of SPE cartridges varying in functionality for the extraction of a wide range of PFAS compounds in water. Data will show spike recovery comparisons between SDVB, WAX and a WAX/GCB stacked column.