Synthesis of a novel diaquabis(1,10-phenanthroline)copper(II)chloride complex and its voltammetric application for detection of amoxicillin in pharmaceutical and biological samples.

A one step facile synthesis of the novel diaquabis(1,10-phenanthroline)copper(II)chloride (APCuC) complex is demonstrated. Cyclic voltammetric and electrochemical impedance spectroscopic results revealed potentiodynamic deposition of a conductive electroactive poly(APCuC) film on the glassy carbon electrode surface increasing its effective surface area. In contrast to the unmodified glassy carbon electrode, appearance of an oxidative peak at a reduced potential with over two fold current for amoxicillin at poly(APCuC)/GCE demonstrated its electrocatalytic property attributed to reduce charge transfer resistance and the improved surface area of the electrode surface. Better correlation of the oxidative peak current with square root of scan rate (R = 0.99779) than with scan rate (R = 0.96953) supplemented by slope of 0.58 for log(current) versus log(scan rate) confirmed diffusion controlled irreversible oxidation of amoxicillin. At optimized solution and SWV parameters, current response of poly(APCuC)/GCE showed linear dependence on concentration of amoxicillin (2.0-100.0 μM) with LoD 0.0115 μM. While no amoxicillin was detected in the human blood serum sample, an amount 89.40-100.55% of the nominal level was detected in the analyzed eight tablet brands. Spike recovery in tablet samples (98.90-101.95%) and blood serum sample (102.20-101.37%); interference with an error (%RSD) of 0.00-4.51% in tablet and 0.00-2.10% in serum samples; excellent stability and reproducible results, added with the wide dynamic range and low LoD validated the method for amoxicillin determination in pharmaceutical formulations and human urine samples.