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Development of a U.S. EPA method to determine total organic fluorine in drinking water by combustion ion chromatography (CIC)
Citation:
Jones, J. AND Dan Tettenhorst. Development of a U.S. EPA method to determine total organic fluorine in drinking water by combustion ion chromatography (CIC). Presented at American Chemical Society Confrence, San Francisco, CA, August 13 - 18, 2023.
Impact/Purpose:
This presentation describes the development of adsorbable organic fluorine and extractable organic fluorine methods combined with combustion ion chromatography to detect total organic fluorine in drinking water. The method development efforts described in this presentation may eventually be used in creating better understanding of total PFAS contamination to help inform decisions on policies for protecting humans from PFAS chemicals in U.S. source water and drinking water.
Description:
The U.S. Environmental Protection Agency’s (EPA) Office of Groundwater and Drinking water (OGWDW) through the Office of Water (OW) is responsible for protecting our nation’s drinking water from contamination. Per and polyfluoroalkyl substances (PFAS) continue to generate concern due to their use in various applications. The National Institute of Environmental Health Sciences states over 9,000 known PFAS compounds exist. Targeted drinking water Methods 533 and 537.1 require an analytical standard for each PFAS compound. The targeted methods can only quantify a small portion of the total possible number of PFAS compounds which is currently about thirty PFAS. In addition, the potential exists for unknown PFAS to be present and undetected. Thus, a method capable of capturing a broader range of PFAS compounds is needed to help drinking water utilities quickly detect potential organic fluorine contamination. Potential methods for determining total organic fluorine in drinking water are under investigation. EPA recently developed draft Method 1621 for determining adsorbable organic fluorine by combustion ion chromatography (AOF-CIC) in 100 mL wastewater samples. Modifications to Method 1621 will be evaluated that might lower the detection limit for use with drinking water. An extractable organic fluorine by combustion ion chromatography (EOF-CIC) method is under development using granular activated carbon combined with anion exchange during solid phase extraction. Cartridges are washed with aqueous ammonia hydroxide to remove inorganic fluoride. Organic fluorine compounds are eluted with a methanolic ammonium hydroxide solution and the extract is analyzed by CIC. Preliminary results show an average recovery of 94.8% with an 18% RSD obtained for 500 mL reagent water samples preserved with ammonium acetate and fortified with a Method 533 PFAS mixture. A discussion of AOF and EOF procedures with recovery and precision data for individual PFAS compounds as well as mixtures of compounds will be presented and compared. The advantages and disadvantages of each technique will be discussed.