The study describes on the preparation of a new homobinuclear mixed ligand complex µ-ethylendiaminetetrakis(1,10-phenanthroline)dicopper(II) chloridedihydrate (EP4Cu2CH2) from a previously reported complex chlorobis(1,10-phenanthroline)copper(II) chloridemonohydrate (CP2CuCH). The synthesis was checked by spectroscopy (UV–Vis, FT IR), CHN elemental analysis, Cu determination using ICP-OES, electrolytic conductivity, qualitative and quantitative chloride estimation, and melting point measurements. The new complex was applied for the modification of a glassy carbon electrode (poly(EP4Cu2CH2)/GCE) for determination of doxycycline (Doxy), (which belongs to a tetracycline antibiotic, mainly used for the treatment of a wide bacterial infections) by selective, accurate, and precise differential pulse voltammetric method. Electrode characterization revealed modification of the electrode surface by a conductive, and electroactive polymer film (poly(EP4Cu2CH2)/GCE) leading to improved effective electrode surface area. In contrast to the bare electrode, the appearance of two well-resolved irreversible oxidative peaks at much reduced potential with sevenfold current enhancement at poly(EP4Cu2CH2)/GCE showed the catalytic effect of the modifier towards Doxy. Differential pulse voltammetric current response of poly(EP4Cu2CH2)/GCE showed a linear dependence on the concentration of Doxy in the range 5 × 10−8 – 3.5 × 10−4 M with a detection limit of 3.5 × 10−9. The Doxy levels in four tablet brands were in the range 96.00–101.30 % of their labeled values. Spike recovery results in tablet, cow milk, and human urine samples were 98.90–100.73 %, 98.30–100.00 %, and 98.50–100.54 %, respectively. Based on the innovative mixed ligand poly(EP4Cu2CH2)/GCE, the interference recovery results about 4.79 % error, lesser LoD, and a broader concentrationrange than most previously published methods validated the present method’s potential applicability with excellent accuracy and sensitivity for Doxy determination in various real samples with complex matrix.
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