This work summarizes the electrochemical response of flavanone carbon composite electrodes in comparison with Nafion ® -coated flavanone carbon composite electrodes, for use as voltammetric pH sensors in both buffered and low-buffered media. Square wave voltammetric measurements suggest the peak potential achieved from the electrochemical polymerization after the electron-proton oxidation responds with accuracy to buffered pH solutions for both coated and non-coated electrodes, with a potential shift of 55.1 mV and 54.6 mV per pH unit respectively. However, a considerable improvement in stability, accuracy and sensitivity is provided by the proton-transfer Nafion ® layer in CO 2 bubbled sea water. Furthermore, Nafion ® -coated flavanone carbon composite electrodes predicted a pH of 8.04 for the commercial seawater, which is in excellent agreement with the measured pH 8.05 value.
This work presents the electrochemical response of a 2‐(methylthio)phenol glassy carbon based electrode for a promising voltammetric pH sensor in both buffered and low‐buffered solutions. Electropolymerization of the redox species was performed with the resulting polymer presenting a Nernstian response in buffered media, with a sensitivity of 51 mV/pH unit. The effectiveness of the sulfhydryl bond to facilitate proton transfer from the bulk solution to the phenol molecules has been confirmed, providing an accurate pH measurement of 8.28 in sea water media, compared to that measured with a calibrated glass pH probe of 8.30.
Reference electrode drift resulting from the exchange of ions at the solution/reference electrode chamber interface is the number one reason why ion selective electrodes and pH sensors in particular require...
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