Development of a Low-Cost Solid-Phase Extraction Method for the Rapid Measurement of PFAS in Environmental Waters

A large class of synthetic compounds known as per- and polyfluoroalkyl substances (PFAS) has become ubiquitous in the environment due to their widespread use and extreme persistence. They pose risks to the environment and human health, drawing significant attention in recent years. Contaminated water consumption has emerged as one of the major pathways for human exposure, and studies have identified elevated PFAS concentrations in human blood linked to polluted drinking water sources. In response to the escalating concern surrounding PFAS, the U.S. EPA has proposed new maximum contaminant levels for six PFAS, notably setting stringent limits of 4 ppt each for PFOA and PFOS. This regulatory advancement, while crucial for public health, introduces challenges in the routine and regular monitoring and detection of PFAS in water samples. Despite the development of various methods for total fluorine measurement and targeted PFAS analysis, those techniques often fall short in achieving the low ppt level required for efficient PFAS measurement or are time-consuming and expensive. As an innovative alternative, particle-induced gamma-ray emission (PIGE) spectroscopy has been developed and employed as a rapid, sensitive, and cost-effective method for screening total adsorbable organic fluorine (AOF) in water samples. The PIGE analysis is integrated with a solid-phase extraction (SPE) method utilizing commercially available and low-cost graphite activated carbon fiber (GACF) felt to pre-concentrate and extract PFAS from water samples before analysis. To accommodate diverse water sample types studied in this research, including drinking water, groundwater, and surface water, the method has been further developed to address various challenges. Specifically, a methanol rinse method distinguishes inorganic fluoride and organic fluorine from PIGE analysis, an acid rinse method differentiates inorganic fluoride and ultrashort-chain PFAS from longer-chain PFAS, and Fenton’s reagent is employed to eliminate water matrix interference.