Electrochemical sensing of PFAS using gold nanoparticle functionalized electrodes
Inventors
Villagran, Dino • Westerhoff, Paul • Calvillo Solis, Jonathan Josue • Wong, Michael
Assignees
William Marsh Rice University • University of Texas System • Arizona State University ASU • Arizona State University Downtown Phoenix campus
Publication Number
US-12241855-B2
Publication Date
2025-03-04
Expiration Date
2043-06-15
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Abstract
A method of electrochemical sensing includes providing an electrochemical sensor comprising a glassy carbon substrate and gold nanoparticles located on a surface of the glassy carbon substrate; and sensing electrochemically a compound selected from the group consisting of polyfluoroalkyl compounds or perfluoroalkyl compounds using the electrochemical sensor. PFOA quantification was performed by Square Wave Adsorptive Cathodic Stripping Voltammetry (SW-AdCSV) in test solutions with a 100-5,000 ppt concentration. The concentration has a linear relationship with the stripping current within this range. Analysis of tap and groundwater samples performed by additions method demonstrated precision and accuracy above 95%. These electrodes show stability throughout 200 cycles, and reproducibility across similarly prepared but different electrodes above 97.5%. Providing the electrochemical sensor can include providing at least one member selected from the group consisting of perfluoro-1-octanethiol (PFTO), 2,2,2-trifluoroethanethiol (TFET) or perfluorodecanethiol (PFDT) on the surface of the glassy carbon substrate.
Core Innovation
The invention provides an electrochemical sensor comprising a glassy carbon substrate with gold nanoparticles located on its surface, for the sensitive detection of compounds including polyfluoroalkyl or perfluoroalkyl substances (PFAS). The sensor is designed for quantifying perfluorooctanoic acid (PFOA) at very low concentrations in aqueous media using techniques such as Square Wave Adsorptive Cathodic Stripping Voltammetry (SW-AdCSV), with a demonstrated linear relationship between stripping current and PFOA concentration in the 100–5,000 ppt range.
The problem addressed by the invention is the need for accurate, precise, rapid, and cost-effective analytical methods for detecting and quantifying persistent and potentially harmful PFAS contaminants, such as PFOA, in environmental and biological samples. Existing methods like liquid chromatography-tandem mass spectrometry (LC-MS/MS) are expensive, time-consuming, and require complex sample preparation, highlighting the demand for simpler alternatives.
The core innovation is the use of electrodeposited gold nanoparticles on glassy carbon electrodes, optionally functionalized with perfluoroalkyl thiols (such as perfluoro-1-octanethiol, 2,2,2-trifluoroethanethiol, or perfluorodecanethiol), to provide high-sensitivity, reproducibility, stability, and selectivity for the electrochemical sensing of PFAS, especially PFOA, even in real-world water samples. The sensors exhibit limits of detection as low as 42.3 ppt, maintain precision and accuracy above 95%, and show stability over repeated sensing cycles.
Claims Coverage
The independent claims in this patent center around three inventive features relating to electrochemical sensing of PFAS using gold nanoparticle-modified electrodes.
Electrochemical sensing of PFAS using gold nanoparticles on glassy carbon
A method involving: - Providing an electrochemical sensor with a glassy carbon substrate and gold nanoparticles deposited on the surface. - Sensing, through electrochemical techniques, a compound selected from the group consisting of polyfluoroalkyl compounds or perfluoroalkyl compounds using the provided sensor.
Electrochemical sensor article with specified nanoparticle density
An article of manufacture comprising: - An electrochemical sensor having a glassy carbon substrate. - A plurality of gold nanoparticles coupled to the surface of the glassy carbon substrate. - The plurality of gold nanoparticles is coupled at a density of approximately 174±07 μm⁻² on the surface.
Electrochemical sensor article with perfluoroalkyl thiol functionalization
An article of manufacture comprising: - An electrochemical sensor with a glassy carbon substrate. - A plurality of gold nanoparticles coupled to the substrate’s surface. - At least one perfluoroalkyl thiol selected from perfluoro-1-octanethiol (PFTO), 2,2,2-trifluoroethanethiol (TFET), or perfluorodecanethiol (PFDT) is coupled to the substrate’s surface.
These inventive features together define methods and articles of manufacture for electrochemical sensors exploiting gold nanoparticle-modified glassy carbon electrodes, optionally with specific perfluoroalkyl thiol modifications, to sensitively and selectively detect PFAS such as PFOA.
Stated Advantages
The electrochemical sensor provides high sensitivity with a low limit of detection and quantification for PFOA and other PFAS in aqueous solutions.
The sensor demonstrates high precision and accuracy, with recovery percentages within 100±5% and relative standard deviations less than 5% in real water samples.
The modified electrodes exhibit excellent stability during repeated use over at least 200 cycles and high reproducibility across different electrodes, with reproducibility variance of 2.44%.
The method reduces analysis time to five minutes or less and lowers per-sample cost compared to conventional methods.
Selectivity for PFOA is enhanced by functionalizing the sensor surface with perfluorodecanethiol, which minimizes interference from other fluorinated compounds.
Documented Applications
Quantitative detection of perfluorooctanoic acid (PFOA) and other polyfluoroalkyl and perfluoroalkyl compounds in aqueous media using electrochemical approaches.
Analysis of tap and groundwater samples for PFOA and PFAS content, demonstrated with standard additions and recovery studies.
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