Bubble-Nucleation-Based Method for the Selective and Sensitive Electrochemical Detection of Surfactants

Abstract

We present the first bubble-nucleation-based electrochemical method for the selective and sensitive detection of surfactants. Our method takes advantage of the high surface activity of surfactant analyte to affect the electrochemical bubble nucleation and then transduces the change in nucleation condition to electrochemical signal for determining the surfactant concentration. Using this method, we demonstrate the quantitation of perfluorinated surfactants in water, a group of emerging environmental contaminants, with a remarkable limit of detection (LOD) down to 30 μg/L and a linear dynamic range of over 3 orders of magnitude. With the addition of a preconcentration step, we have achieved the LOD: 70 ng/L, the health advisory for perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA) in drinking water established by the U.S. Environmental Protection Agency. The experimental results are in quantitative agreement with our theoretical model derived from classical nucleation theory. Our method also exhibits an exceptional specificity for the surfactant analytes even in the presence of 1000-fold excess of nonsurfactant interference. This method has the potential to be further developed into a universal electrochemical detector for surfactant analysis because of its simplicity and the surface-activity-based detection mechanism.

Recent Developments of PFAS-Detecting Sensors and Future Direction: A Review

“…With the increasing urgency in developing versatile and reliable detection methods, a trend in sensor development for PFAS determination was investigated in the literature. In more recent years, research has been focused on developing on-site detection methods, such as ion-selective electrode (ISE) [ 76 , 77 ], electrochemical sensors [ 78 , 79 , 80 ], fluorescence sensors [ 79 ], and smartphone app-based monitoring systems [ 75 ], that are both reliable and more economically feasible than conventional methods. Examples of these detection methods, along with their LODs, are outlined in Table 2 .…”

“…However, to avoid complications associated with low electroactivity, a bubble-nucleation-based electrochemical method that detects concentrations of PFASs based on their high surface activity has also been proposed [ 80 ]. The method, proposed by Ranaweera et al, consists of applying a sub-50-nm Pt nanoelectrode to an acidic solution, which causes hydrogen evolution reactions (HERs), resulting in a measurable current upon negatively scanning the nanoelectrode potential until it reaches a peak value ( i peak ) [ 80 ]. As shown in Figure 3 , the sudden drop in the HER current past the peak corresponds to the formation of an H 2 gas bubble at the electrode, thereby blocking the electrode surface.…”

Lowering Interfacial Dissolved Gas Concentration for Highly Efficient Hydrazine Oxidation at Platinum by Fluorosurfactant Modulation

“…The Pt nanoelectrode radius was estimated from the diffusion-limited current for proton reduction ( Figure S7). [21] The Pt nanoelectrode was then employed to study the N 2 bubble nucleation from electrooxidation of hydrazine. Figure 1A shows the cyclic voltammogram (CV) of a 19-nmradius Pt nanoelectrode in a 0.5 M H 2 SO 4 solution containing 1 M N 2 H 4 .…”

Detection of Perfluorooctane Sulfonate by Ion-Transfer Stripping Voltammetry at an Array of Microinterfaces Between Two Immiscible Electrolyte Solutions

“…Another approach is to use an extraction method to isolate the target analyte from the sample matrix prior to electrochemical measurement, as employed recently by Luo and colleagues, 48 who combined solid-phase extraction of PFASwith a bubble nucleation electrochemical detection method. Table 1.…”

“…Using a rotated electrode to improve mass transport to this ITIES and a preconcentration time of 30 min, they reported a LOD of 50 pM PFOSion in the presence of millimolar background electrolyte. 26 As an indication of interest in electrochemical approaches for PFOSdetection, recent papers reported its detection with LODs of 140 pM (using an electrochemical bubble nucleation method), 48 40 pM (with a molecularly-imprinted polymer electrode) 49 and 1 pM (using a metal-organic framework impedimetric device). 50 Based on these antecedents, here we propose an electroanalytical approach for PFOSemploying a ITIES array: by exploiting the enhanced (radial) diffusion at microinterfaces, the need for electrode rotation and long preconcentration times is removed, resulting in a simpler analytical strategy.…”