Simultaneous and interference-free detection of hydroquinone and catechol on poly (Evans Blue)-Modified Glassy Carbon Electrode

A simple and sensitive electrochemical sensor for the simultaneous detection of hydroquinone (HQ) and catechol (CT) is developed based on a poly (Evans blue) (PEB)-modified anodized glassy carbon electrode (AGCE). The PEB/AGCE sensor shows excellent electrocatalytic activity and reversibility toward the oxidation of both HQ and CT in phosphate buffer solution (PBS, pH 7.0). Both AGCE and PEB/AGCE can easily resolve the redox responses of HQ and CT from their mixture solution with the same peak-to-peak potential (AE_p) separations of ca. 0.10 V, whereas bare GCE cannot resolve them. The PEB/AGCE sensor exhibits significantly higher sensitivity with a linear dynamic range 1-100 \xM for both HQ and CT. Furthermore, the sensor shows detection limits (S/N = 3) of ca. 0.13 and 0.12 \xM for HQ and CT, respectively, with sensitivities of ca. 1.01 and 0.95 \iA/cm²/\iM, respectively. The sensor does not exhibit any significant interference for the detection of HQ and CT in the presence of common interferences. This study provides a simple and sensitive method with excellent recoveries for the simultaneous and quantitative determination of HQ and CT from tap water.