May 13, 2022
Draft Method 1621 is intended for screening organofluorine compounds in water & wastewater
In April, the U.S. Environmental Protection Agency (EPA) Office of Water published Draft Method 1621: "Screening Method for the Determination of Adsorbable Organic Fluorine (AOF) in Aqueous Matrices by Combustion Ion Chromatography (CIC)." This is the latest development in EPA's commitment to establish methods for measuring per- and polyfluoroalkyl substances (PFAS) in the environment, with potential implications for monitoring wastewater and industrial discharges.
This draft analytical method is designed to screen water and wastewater for compounds containing carbon-fluorine bonds. As a screening method, the protocol quantifies the concentration of fluoride remaining in a water sample following the combustion of all organic material containing fluorine. As such, the method generally quantifies the amount of PFAS as well as non-PFAS compounds containing at least one carbon-fluorine bond, including some pharmaceuticals, pesticides, and refrigerants (e.g., Freon). The method can detect organic fluorine at the parts-per-billion (ppb) level in water samples, which is three orders of magnitude less sensitive than other methods that target specific PFAS compounds in water samples at the parts-per-trillion (ppt) level.
Total organic fluorine analyses have been gaining traction recently but largely for consumer products, not for environmental samples.
Before publishing Draft Method 1621, no official EPA method was available for this type of analysis.
According to EPA, Draft Method 1621 is intended for use in water and wastewater monitoring to "broadly screen for thousands of known PFAS compounds." Screening-level methods are often employed in environmental sample characterization as a "first pass" to determine whether a type of compound may be present. The sample can then be further analyzed for a suite of known chemicals using validated methods, known as a targeted analysis.
In the case of Draft Method 1621, EPA is likely to employ the method to screen industrial wastewater discharges for elevated levels of organofluorine compounds. Should the analysis detect organic fluorine, a likely next step would be to analyze the sample with EPA's Draft Method 1633, which targets and quantifies 40 individual PFAS compounds.
Confirming the results of the organic fluorine method with a targeted analysis of known PFAS compounds is particularly important given the potential presence of non-PFAS compounds, such as pharmaceuticals and refrigerants, in environmental samples, and potential method interference with naturally occurring inorganic fluoride, organic carbon, or elevated chloride. It will likely take some time to understand how the two methods will be used in conjunction with one another, either through compliance monitoring or National Pollutant Discharge Elimination System permits.
How Exponent Can Help
Exponent's expert consultants in analytical chemistry and regulatory compliance can help clients stay ahead of the rapid developments in PFAS test methods and their potential business impacts. Our multidisciplinary team of environmental scientists and analytical chemists can assess organic fluorine data, facilitate laboratory testing for PFAS analysis, evaluate permitting requirements, and validate PFAS data to ensure usability and compliance. Our experts can also assist in source identification, chemical fingerprinting, and fate and transport analyses of PFAS in the environment, as well as in reviewing and commenting on proposed state and federal regulations for PFAS compounds.