Graphene-Based Electrochemical Sensors for the Determination of Pharmaceutical- and Agricultural-Based Emerging Contaminants in Water

> 0.99) across a wide dynamic range and strong agreement with HPLC-MS analysis. Under optimized electro-Fenton (EF) conditions, additional ECs─including diclofenac, ibuprofen, glyphosate, and estradiol─showed comparable responses, demonstrating broad applicability independent of molecular structure. Mass spectrometry confirmed peroxide-driven radical transformation of AMX, revealing hydroxylated derivatives and β-lactam ring-opened intermediates consistent with reactive oxygen species (ROS) chemistry. Unlike targeted chromatographic approaches, the electrochemical signal reflects the integrated pool of peroxide-reactive species, including transformation products not directly quantified by conventional methods. Application to real wastewater samples showed that the EF-assisted electrochemical response captures a broader oxidizable organic load than targeted HPLC-MS/MS. These findings establish peroxide-assisted graphene electrodes as a sensitive, low-cost, and field-deployable platform for rapid screening of total oxidizable contaminant burden in complex water matrices.