Electrochemical behavior of catechol, resorcinol and hydroquinone at graphene–chitosan composite film modified glassy carbon electrode and their simultaneous determination in water samples

Graphene–chitosan composite film modified glassy carbon electrode was prepared and characterized. The fabricated electrode showed excellent electrochemical catalytic activities towards the oxidation of catechol (CT), resorcinol (RS) and hydroquinone (HQ). The oxidation overpotentials of CT, RS and HQ decreased significantly and the corresponding oxidation currents increased remarkably compared with those obtained at the bare GCE and chitosan modified GCE. Some kinetic parameters , such as the electron transfer number ( n ), proton transfer number ( m ), charge transfer coefficient ( α ) and the apparent heterogeneous electron transfer rate constant ( k s ), were calculated. Differential pulse voltammetry was used for the simultaneous determination of CT, RS and HQ in their ternary mixture . The peak-to-peak potential separations between CT and RS, RS and HQ, and HQ and CT were 0.388, 0.484 and 0.096   V, respectively. The calibration curves for CT, RS and HQ were obtained in the range of 1   ×   10 −6 to 4   ×   10 −4 , 1   ×   10 −6 to 5.5   ×   10 −4 and 1   ×   10 −6 to 3   ×   10 −4   mol   L −1 , respectively. The detection limits were 7.5   ×   10 −7   mol   L −1 ( S / N   =   3).