A magnetic bar carbon paste electrode (MBCPE) modified with cobalt ferrite magnetic electrospun nanofibers (NFs) and graphene oxide (GO) is described for the electrochemical determination of rutin. The NFs were prepared by electrospinning using a solution that contains poly(vinyl pyrrolidone) (PVP) and Co(II) and Fe(III) nitrates as metal sources. Carbon paste was prepared by hand mixing GO, CoFe2O4 NFs and graphite. This paste was then packed into the end of a glass tube and a very small magnetic bar was inserted into the tube to be coated with the carbon paste to provide a magnetic field. The MBCPE was used to attract the magnetic nanofibers to the electrode surface. Cyclic voltammetry and differential pulse voltammetry techniques were used to study the electrochemical behavior of rutin on the modified MBCPE at pH 2.5. The electrocatalytic current, best measured at a potential of around 0.5 V (vs. Ag/AgCl), varies with the rutin concentration in two linear ranges, viz. from 0.001-0.1 nM and from 1.0-100 nM, with a 0.94 pM detection limit. The electrode was successfully applied to the determination of rutin in lemon, red apple, lime and orange juices. Graphical abstractSchematic representation of a modified magnetic bar carbon paste electrode for detection of rutin. To achieve the modified electrode, electrospun CoFe2O4 nanofibers, graphene oxide and a very small magnetic bar are packed into the end of a glass tube.
Keywords: Electrospinning; Flavonoids; Magnetic bar carbon paste electrode; Metal oxide; Modified electrode; Nanoprobe; Spinel ferrites; Voltammetry.