Immobilization of Ru(II) Complex Onto the Glassy Carbon Electrode for the Detection of Tetracycline Residue in Chicken Egg and Cow Milk

This study highlights the electrochemical drug (ECD) sensor with a glassy carbon electrode modified with ruthenium(II) complex (RBNH), which showed a stronger response to the detection of tetracycline (TC) antibiotic residue in real samples like chicken eggs and cow milk compared to other substrate materials. Glassy carbon electrodes are covalently functionalized with ruthenium(II) complex containing the redox active 2, 2 bipyridine, and a hydrazone ligand (BNH) via., drop casting method. This results in the electrocatalytic behavior of the modified electrode (GCE/RBNH) on the oxidation of TC. Further, the modified electrode′s sustainability was tested with various antibiotics, including different concentrations of tetracycline, and scan rates by different techniques like cyclic voltammetry (CV), linear sweep voltammetry (LSV). Then a GCE/RBNH was used to create a linear calibration curve for TC concentrations ranging from 10 to 100 μmol L⁻¹ (R²=0.99), with a limit of detection and quantification 0.0675 μmol L⁻¹ and 0.224 μmol L⁻¹. The current approach, which possesses an effortless electrode modification step and offers the lowest detection limit and a comparatively wider linear dynamic range, performed better for determining TC in chicken eggs and milk samples than recently reported voltammetric methods.