Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States.
Lineberger Comprehensive Cancer Center, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States.
Anal Chem. 2020 Aug 4;92(15):10597-10605. doi: 10.1021/acs.analchem.0c01565. Epub 2020 Jul 13.
Per- and polyfluoroalkyl substances (PFAS) are emerging as harmful environmental micropollutants. Generally, PFAS species are quantified by mass spectrometry, for which a collected sample is taken to a centralized facility. Robust techniques to quantify PFAS in the field are necessary to diagnose environmental contamination at the earliest onset of pollution. Here, we developed a molecularly imprinted polymer (MIP) electrode for the detection of perfluorooctanesulfonate (PFOS) and explored the MIP surface and the effects of interfering molecules. MIPs were formed by the anodic deposition of -phenylenediamine (-PD) in the presence of PFOS template molecules on a glassy carbon macroelectrode. The performance of the resulting MIP electrode was evaluated by the current obtained from the oxidation of ferrocene carboxylic acid as the electrochemical probe. The MIP electrode was able to detect PFOS with a detection limit of 0.05 nM, which is lower than the health advisory limit of 0.14 nM reported by the U.S. EPA. To better understand PFOS association into the MIP, a Langmuir binding model was developed based on the changes in electrochemical responses of the MIP. Fitting the model to the experimental data gave an association constant () of 4.95 × 10 over a PFOS concentration range of 0 to 0.05 nM. The binding isotherm of other commonly found substances in contaminated water sources such as chloride, humic acid, perfluorooctanoic acid (PFOA), and perfluorobutanesulfonate (PFBS) was also investigated. In the case of chloride and humic acid, the calculated values of 9.05 × 10 and 6.01 × 10, respectively, indicate relatively weak adsorption of these species on the MIP. However, PFOA, which is the carboxylate analog of PFOS, revealed a very close value (3.41 × 10) to PFOS. A greater value (1.43 × 10) was obtained for PFBS, which possesses the same functional group and a smaller molecular size compared to PFOS. The presented platform emphasizes the necessity to develop new strategies to make MIP sensors more specific if practical applications are to be pursued.
全氟和多氟烷基物质（PFAS）正在成为有害的环境污染物。通常，通过质谱法对 PFAS 物质进行定量分析，为此需要将采集的样本送到集中设施。需要强有力的技术来现场量化 PFAS，以便在污染最初发生时就诊断出环境污染。在这里，我们开发了一种用于检测全氟辛烷磺酸（PFOS）的分子印迹聚合物（MIP）电极，并探索了 MIP 表面和干扰分子的影响。在存在 PFOS 模板分子的情况下，通过在玻碳宏观电极上阳极沉积 -苯二胺（-PD）来形成 MIP。通过将电化学探针二茂铁羧酸的氧化所产生的电流来评估所得 MIP 电极的性能。MIP 电极能够检测到 PFOS，其检测限为 0.05 nM，低于美国环保署报告的 0.14 nM 的健康建议限值。为了更好地理解 PFOS 与 MIP 的结合，根据 MIP 电化学响应的变化，开发了一个 Langmuir 结合模型。将模型拟合到实验数据给出了在 0 到 0.05 nM 的 PFOS 浓度范围内的结合常数（）为 4.95×10。还研究了其他常见于污染水源中的物质（如氯离子、腐殖酸、全氟辛酸（PFOA）和全氟丁烷磺酸（PFBS））的结合等温线。在氯离子和腐殖酸的情况下，分别计算出的值为 9.05×10 和 6.01×10，表明这些物质在 MIP 上的吸附相对较弱。然而，PFOA 是 PFOS 的羧酸类似物，与 PFOS 的 值非常接近（3.41×10）。对于 PFBS，得到了更大的值（1.43×10），因为它具有相同的官能团和比 PFOS 更小的分子尺寸。所提出的平台强调，如果要进行实际应用，有必要开发新的策略来使 MIP 传感器更具特异性。
