Dispersive Liquid-liquid Micro-extraction for the Automated Sample Preparation of PFAS as a Viable Alternative to Solid Phase Extraction Techniques

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

Presented by C. Grim
Prepared by E. George1, J. Moriceau2, A. Ganci2, J. Garnier3
1 - Thermo Fisher Scientific, 55 River Oaks Pkwy, San Jose, CA, 95134, United States
2 - Thermo Fisher Scientific, Thermo Fisher Scientific, Courtaboeuf, , France
3 - Thermo Fisher Scientific, , Courtaboeuf, , France


Contact Information: [email protected]; 408-300-4267

ABSTRACT

Per- and polyfluoroalkyl substances (PFAS) are a group of man-made chemicals that have been in use since the mid-20th century in various industries due to their resistance to heat, water, and oil. However, their environmental persistence and potential adverse health effects have led to a growing concern about PFAS contamination monitoring in the environment.

Solid phase extraction with WAX or other sorbents are a common approach used in many published methods to concentrate and clean up aqueous samples to obtain required low part-per-trillion reporting levels in LC-MS/MS analysis. The technique, however, is labor intensive, prone to background contamination from SPE cartridges and sorbents, and can provide poor precision among operators especially when performed on manual extraction manifolds with large volumes of samples (exp 200-500 mL). Automated systems have been developed for large sample volumes, but they are tied to costly SPE extraction cartridges which consume large volumes of solvent, are limited to less than 10 sample positions, and need extensive rinsing of all positions to reduce or eliminate carryover.

Dispersive liquid-liquid microextraction (DLLME) is a highly effective sample preparation technique that has gained significant attention in analytical chemistry, since its first publication in 2006, due to its simplicity, low cost, robustness, and high enrichment factors. DLLME is a miniaturized form of liquid-liquid extraction that uses minimal amounts of extraction solvent, making it a greener and environmentally friendly alternative. Briefly, a small volume of sample with labeled internal standards (15 mL) is acidified, then a specific dispersant and extractant are added to the sample and vortexed to form a cloudy solution. It is then centrifuged, and the top separated organic layer is moved to another vial to which a secondary extractant is added, vortexed, and centrifuged. The PFAS contained in the extractant layer at the bottom of the vial is injected into the LCMS system. All of this is done automatically with full control by Chromelon CDS in combination with a Thermo Scientific™ TriPlus™ RSH SMART robotic autosampler.
Data will be presented on the technique in terms of PFAS sensitivity, calibration range, precision, and accuracy for matrices including drinking water, groundwater, surface water, and wastewater