Schiff Base‐Modified Chitosan Electrochemical Sensor for the Simultaneous Determination of Phenolic Isomers

ABSTRACT

This study reports a pyrene‐Schiff‐base‐modified chitosan (CH‐Py) layer deposited on a commercial screen‐printed carbon electrode (SPCE) for the simultaneous electrochemical response to hydroquinone (HQ), catechol (CC), and resorcinol (RS). Bare SPCE, chitosan‐modified SPCE (CH/SPCE), and CH‐Py/SPCE were compared, and cyclic voltammetry (CV), scan‐rate experiments, and electrochemical impedance spectroscopy (EIS) were performed in a mixed phenolic solution. CH‐Py/SPCE showed separated oxidation signals for HQ, CC, and RS, with detection limits of 3.4, 4.3, and 2.7 µM, respectively. The response is discussed as an analyte‐mediated interfacial effect, which may arise from the combined effects of analyte accumulation, modified interfacial environment, and facilitated charge‐transfer behavior. A spiked lake‐water recovery experiment for RS in the presence of fixed HQ and CC gave a mean recovery of 93.74 ± 5.43% ( n  = 3). Five‐day storage, repeatability, and inter‐electrode reproducibility tests provided preliminary operational‐performance information. This work demonstrates proof‐of‐concept peak discrimination in a ternary mixture and a preliminary spiked environmental‐water application.