Investigation of the adsorption/desorption mechanism of perfluoroalkyl substances on HLB-WAX extraction phases for microextraction

Aghogho A Olomukoro; Charlotte DeRosa; Emanuela Gionfriddo

doi:10.1016/j.aca.2023.341206

Investigation of the adsorption/desorption mechanism of perfluoroalkyl substances on HLB-WAX extraction phases for microextraction

Anal Chim Acta. 2023 Jun 15:1260:341206. doi: 10.1016/j.aca.2023.341206. Epub 2023 Apr 10.

Authors

Aghogho A Olomukoro¹, Charlotte DeRosa², Emanuela Gionfriddo³

Affiliations

¹ Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH, 43606, USA; Dr. Nina McClelland Laboratories for Water Chemistry and Environmental Analysis, The University of Toledo, Toledo, OH, 43606, USA.
² Dr. Nina McClelland Laboratories for Water Chemistry and Environmental Analysis, The University of Toledo, Toledo, OH, 43606, USA; College of Pharmacy and Pharmaceutical Sciences, The University of Toledo, Toledo, OH, 43606, USA.
³ Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH, 43606, USA; Dr. Nina McClelland Laboratories for Water Chemistry and Environmental Analysis, The University of Toledo, Toledo, OH, 43606, USA; School of Green Chemistry and Engineering, The University of Toledo, Toledo, OH, 43606, USA. Electronic address: emanuela.gionfriddo@utoledo.edu.

PMID: 37121661
DOI: 10.1016/j.aca.2023.341206

Abstract

The C-F alkyl structural backbone of per- and polyfluoroalkyl substances makes this class of molecules resistant to heat and degradation, leading to their high persistence and mobility in the environment and bioaccumulation in the tissues of living organisms. In this study, 15 PFAS with an alkyl chain length from C₄ to C₁₄, currently monitored by the U.S. Environmental Protection Agency (EPA), were preconcentrated by solid-phase microextraction (SPME) and analyzed by liquid chromatography-tandem mass spectrometry. The adsorption and desorption mechanisms of PFAS onto ion-exchange extraction phases was evaluated to understand the extraction process of PFAS from various environmental matrices under different conditions. This was achieved using two SPME geometries, namely fibers and thin films. The use of thin films resulted in a twofold improvement in extraction efficiency compared to fibers, especially for the short-chain PFAS. Methanol:water (80:20, v/v) was chosen as the optimized desorption solution, with ammonium formate added to minimize carryover. Extraction time profiles for both SPME geometries showed faster equilibration with thin films (30 min) compared to fibers (90-120 min). The linear dynamic range obtained with this method using fibers and thin films ranged from 10 to 5000 ng L^-1 and 2.5-5000 ng L^-1, respectively, with acceptable accuracy (70-130%) and precision (<15%). LOD ranged within 2.5-10 ng L^-1 for fibers and 0.01-0.25 ng L^-1 for thin films. Investigating the factors affecting PFAS recovery in complex samples enabled the quantitative assessment of PFAS contamination in various environmental water samples such as seawater, melted snow and biospecimens like human plasma. A 96-SPME holder was used for validation, which is compatible with sampling in 96-well plates and ensures high throughput in the analysis of real samples. The total concentration of PFAS detected in seawater and snow was 51.3 ng L^-1 and 16.4 ng L^-1, respectively.

Keywords: Ion-exchange sorbents; Perfluoroalkyl substances; Solid phase microextraction.