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

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 mu g/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.