Table S1: Chemical sample table indicating corresponding CAS, supplier and other details. Table S2: Experimental sample table for composition analysis using binding energies of GO and RGO by XPS. Table S3: Experimental sample table for the modified glassy carbon electrode electrochemical characteristics. Figure S1: CV of ERGO/GCE at different scan rates (10–300 mV/s) in 1.0 mM K₃Fe(CN)₆ solution with 1 M KCl. Figure S2: (A) Storage stability of the proposed sensing matrix (ERGO/GCE), (B) SWV of PT (1.5, 2.5, 5 μM) added in groundwater. Figure S3: (A) Absorption spectra of parathion and (B) corresponding calibration plot.

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