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WAIT-CBI-2021.02.23_CCO.p26_Dr.SusanRichardsonLetterToNCDEQReDeadlineExtension February 23, 2021 Sheila C. Holman Assistant Secretary for the Environment NC Department of Environmental Quality 1601 Mail Service Center Raleigh, NC 27699 Re: Additional information requested per the 6-month extension request Dear Ms. Holman, I was forwarded a message that you needed the following information in regard to my request for a 6 month extension of our project, ‘Development of a Total Organic Fluorine (TOF) Method for the Analysis of Process Wastewater Streams and Air from Fayetteville Works (NC)’, to December 31, 2021. • More updated information on progress made to date; • A schedule and timeline of actions to be taken between now and Dec 31. As mentioned in my previous letter, the continuing covid pandemic has limited our capacity in the laboratory, also including not receiving research supplies on a timely basis. We are providing below more updated information on our progress and a schedule and timeline of actions we will take between now and December 31. Please note that some of the information being provided is considered to be R&D proprietary. We can provide further details if needed. More Information on Progress Since the last progress report on December 20, 2020, our research focus has been primarily on pushing to finish optimizing the Absorbable Organic Fluorine (AOF) extraction method. A large part of this push has focused on ensuring that the final method can reliably remove higher levels of inorganic fluorine that may be present in real environmental samples. We recently learned that the concentration of inorganic fluorine present may be much higher than what current experiments for AOF optimization have shown the capability to remove. We have also found that some PFAS standards can also contain inorganic fluorine, which can result in falsely high percent recoveries of organic fluorine during method optimization experiments, making it difficult to reliably distinguish between inorganic and organic fluorine for optimization. Our current focus is placed on receiving new PFAS standards and conducting several experiments with the goal of removing higher concentrations of inorganic fluorine in samples. Current Progress to Date: AOF Activated Carbon (AC) Extraction Optimization of IC instrument methods for optimal fluoride sensitivity and separation (column selection, eluent conditions, sample volume injection, etc.) System and method background analysis for inorganic fluorine pH adjustment of sample before extraction Activated carbo (AC) composition Number of AC columns needed Varying rinsing solutions as well as a sample pretreatment step to remove inorganic fluorine have been tested Volume of aqueous absorption solution Composition and pH of aqueous absorption solution Combustion time Parameters Left to Optimize: AOF AC Extraction Sample holding time Sample volume (potential for dilution) Volume of rinsing solution Combustion temperature Current Progress to Date: Extractable Organic Fluorine (EOF) Solid Phase Extraction (SPE) Optimization of ion chromatography (IC) conditions for optimal fluoride sensitivity and separation as stated in above AOF method Several different SPE phases have been purchased including a new phase not listed in the original proposal Phases have been compared for their ability to rinse and not retain inorganic fluorine Experiments for optimizing elution steps have begun Composition and pH of absorption solution Parameters Left to Optimize: EOF SPE Sample holding time pH of sample before extraction Volume of sample/whether to dilute SPE phases will be compared later on using various parameters to help pick the best suited phase SPE elution conditions will continue to be optimized Temperature and time of combustion will be re-evaluated for quartz wool combustion, but is expected to be similar to the AOF method ANTICIPATED (QUARTERLY) MILESTONES: March 31, 2021: Evaluation of AOF sample volume (dilution), rinsing solution volume and composition, and inorganic fluorine removal from samples June 31, 2021: Evaluation of SPE sample pH, sample volumes, elution conditions, and combustion time and temperature September 30, 2021: Evaluation of sample holding times and temperature for both AOF and EOF methods and comparison of methods with UPLC-MS/MS analysis of known standards December 31, 2021: Final report for optimized method Please let us know if the extension request is acceptable. Sincerely, Susan D. Richardson, Ph.D. Arthur S. Williams Professor of Chemistry Department of Chemistry and Biochemistry University of South Carolina