Characterization and Application of a Synthesized Novel Poly(chlorobis(1,10-phenanthroline)resorcinolcobalt(II) chloride)-Modified Glassy Carbon Electrode for Selective Voltammetric Determination of Cefadroxil in Pharmaceutical Formulations, Human Urine, and Blood Serum Samples

[Image: see text] Cefadroxil belongs to the β-lactam antibiotics, mainly used for the treatment of various bacterial infections, caused by Gram-positive and Gram-negative bacteria. However, it is also encountering serious bacterial resistance, necessitating continuous monitoring of its level in pharmaceutical and biological samples. This study presents a selective, accurate, and precise square-wave voltammetric method based on a novel poly(chlorobis(1,10-phenanthroline)resorcinolcobalt(II)chloride)-modified glassy carbon electrode (poly(CP(2)RCoC)/GCE) for determination of cefadroxil (CDL). UV–vis spectroscopy, FT-IR spectroscopy, metal and halide estimation, CHN elemental analysis, and electrolytic conductivity measurement results confirmed the synthesis of the title complex modifier. Electrode characterization results revealed modification of the surface of the electrode by an electroactive and a conductive polymer film (poly(CP(2)RCoC)/GCE), leading to an improved effective electrode surface area. In contrast to the bare electrode, the appearance of an irreversible oxidative peak at a much reduced potential with a 7-fold current enhancement at poly(CP(2)RCoC)/GCE showed the catalytic effect of the modifier toward oxidation of CDL. The square-wave voltammetric current response of poly(CP(2)RCoC)/GCE showed a linear dependence on the concentration of CDL in the range of 1 × 10(–7)–3.0 × 10(–4) M with a detection limit of 4.3 × 10(–9). The CDL level in the selected two tablet brands was in the range of 97.25–100.00% of their labeled values. The spike recovery results in tablet, human blood serum, and urine samples were 98.85–101.30, 99.20–100.39, and 98.10–99.99%, respectively. Interference recovery results with a less than 4.74% error, lower LoD, and wider dynamic range than the previously reported methods validated the potential applicability of the present method with excellent accuracy and sensitivity based on the novel mixed-ligand complex-modified GCE (poly(CP(2)RCoC)/GCE) for determination of CDL in various real samples with a complex matrix.