Use of electrochemically pretreated glassy carbon electrodes as pH sensors in potentiometric titrations

The potentiometric response of glassy carbon (GC) electrodes pretreated by cycling consecutively the potential in the range 0.2 to −0.8 V was examined. The electrochemical treatment creates microchannels at the electrode surface through which cations may intercalate. A linear response to H+ ions concentrations in the range 10−2 to 10−5 M was observed, with a slope of 60 mV per pH and a response time of 40 s for 80% response. The electrode showed an excellent performance in pH potentiometric titrations, results for synthetic and real acid samples being in agreement with those obtained by using a glass electrode. Cross-sensitivity tests for other cations (Na+, K+ and Ba2+) were also performed and the results indicated a correlation between the solvated ionic radius and the intercalation effect responsible for the sensor’s response.