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.

一类被称为全氟和多氟烷基物质（PFAS）的合成化合物在环境中普遍存在，这主要归因于它们广泛的应用和极端的持久性。这类物质对环境和人类健康构成风险，近年来引起了广泛关注。受污染的水源消费已成为人类暴露的主要途径之一，研究表明，与受污染饮用水源相关的人类血液中PFAS浓度升高。为了应对对PFAS日益加剧的担忧，美国环保署（U.S. EPA）提出了六种PFAS的新最大污染物水平，其中特别设定了PFOA和PFOS的严格限制，即每份4 ppt。尽管这一监管进步对于公共卫生至关重要，但在水样中常规和定期监测和检测PFAS时也引入了挑战。尽管开发了各种总氟测量和目标PFAS分析的方法，但这些技术往往无法达到高效PFAS测量所需的低ppt水平，或者耗时长且成本高昂。作为一种创新的替代方案，粒子诱导伽马射线发射（PIGE）光谱学已被开发并应用于作为快速、灵敏且经济的筛查水样中总可吸附有机氟（AOF）的方法。PIGE分析集成了利用市售低成本石墨活化碳纤维（GACF）毡的固相萃取（SPE）方法，以预浓缩和提取水样中的PFAS。为了适应本研究中研究的水样类型多样性，包括饮用水、地下水和地表水，该方法已被进一步开发以应对各种挑战。具体而言，甲醇冲洗法可区分无机氟和有机氟，酸冲洗法可区分无机氟和超短链PFAS与长链PFAS，而费顿试剂被用于消除水基质干扰。