Preparation of γ-Fe2O3/hydroxyapatite/Cu(II) magnetic nanocomposite and its application for electrochemical detection of metformin in urine and pharmaceutical samples

In this work, an electrochemical sensor based on carbon paste electrode (CPE), modified with gamma-Fe2O3@ hydroxyapatite/Cu(II) nanocomposite [gamma-Fe2O3 @HAp/Cu(II)], was prepared and used for the determination of metformin (MET). The synthesized nanocomposite was carefully characterized by FTIR, SEM, EDX, TEM and VSM. The electrocatalytic oxidation of MET on the modified CPE was investigated by cyclic voltammetry (CV) and adsorptive stripping differential pulse voltammetry (ASDPV). The results showed that the gamma-Fe2O3@HAp/Cu (II) modified CPE [gamma-Fe2O3@HAp/Cu(II)-CPE] could effectively enhance the electrochemical detection performance towards oxidation of MET. The proposed sensor revealed a good linear relationship between the peak current and the MET concentration in the range from 0.1 to 80 M. The detection and quantification limits were estimated as 14 nM (S/N = 3) and 141 nM (S/N = 10), respectively. The system provides good precision with relative standard deviation of less than 4.0%. Moreover, the proposed MET sensor has also been successfully applied to the direct assays of pharmaceutical and urine samples. The simple, accurate and precise quantification of metformin makes the gamma-Fe2O3@HAp/Cu(II)-CPE system of great interest for monitoring its therapeutic use.