Validation of Analysis of Per- and Polyfluoroalkyl Substances in Wastewater Samples Using EPA Method 1633 with Semi-Automated Solid Phase Extraction

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

Prepared by T. Hall, R. Addink
Fluid Management Systems, 900 Technology Park Dr, Billerica, MA, 01821, United States


Contact Information: [email protected]; 617-393-2396

ABSTRACT

The United States Environmental Protection Agency (US EPA) released the most recent draft of Method 1633 last year which will focus on testing for 40 native Per- and Polyfluoralkyl Substances (PFAS) compounds in biosolids, fish tissue, ground water, landfill leachate, soil, surface water, and wastewater. The list of PFAS compounds is more extensive than existing methods 533 and 537.1 and the new 1633 method can be used for a wide variety of matrices.

For water samples Solid Phase Extraction (SPE) has developed over the last few decades into a fast and reliable method to analyze water samples for a wide variety of chemicals. Many environmental laboratories have specifically a need for high throughput of water samples being analyzed for PFAS. This includes both drinking- and wastewater. A semi-automated technique for Solid Phase Extraction of PFAS compounds in water was developed which is inexpensive and has little chance of mechanical breakdown, the only automated part being a vacuum pump. A complete validation of method 1633 using this system was carried out.

Twelve wastewater samples (500 mL) spiked with PFAS standards can be run on the system in parallel using Weak Anion Exchange (WAX) cartridges. Chemicals used are 1% methanolic ammonium hydroxide, formic acid in water, reagent water and formic acid in methanol. The system uses a vacuum pump for most of the steps: conditioning, sample loading, drying and elution. Bottle rinses were done with nitrogen. Extracts were collected in polypropylene tubes and as per the method no further concentration was carried out. Relevant recovery standards were added prior to LC/MS analysis.

An important problem with ground- and wastewater extraction is the presence of particulate matter which can easily plug up cartridges. Use of plastic filtration wool in the barrel of the cartridges can eliminate this problem. In this work no clogging of cartridges was observed.

Wastewater samples can be analyzed with USEPA method 1633 using a simple laboratory semi-automated SPE set-up. Recoveries were excellent with almost all values > 90%. RSDs observed were < 9 %. The system described here is an inexpensive alternative to fully automated SPE instrumentation.