A simple, sensitive and efficient electrochemical platform based on carbon paste electrode modified with Fe3O4@MIP and graphene oxide for folic acid determination in different matrices

A new biomimetic sensor selective to folic acid based on a carbon paste modified with graphene oxide and Fe3O4 nanoparticles coated with molecularly imprinted polymer in the core@shell format (Fe3O4@MIPs) was obtained using the polyol method. The sensing phase was synthesized in a simple way and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Brunauer-Emmett-Teller (BET) surface area. In the binding experiments the selective material showed a high adsorption capacity (Q) of 30.4 mg g−1 for MMIP, while the Q value for MNIP (magnetic non-imprinted polymer) was 15.3 mg g−1 both of them following the Langmuir model to the adsorption procedure. After their efficiency was proven, these materials were used as modifiers in the electrochemical sensor (Fe3O4@MIP-GO/CPE). Under optimized conditions using the square-wave adsorptive voltammetry, the proposed sensor exhibited excellent response with a concentration linear range between 2.5 and 48 μmol L−1 and limit of detection of 0.65 μmol L−1 (S/σ = 3). The advantages obtained with the proposed method were high robustness, selectivity, and low cost being these characteristics due to the MIP; highly sensibility due to the high superficial area being the contribution of the magnetite in the core of material; and experimentally versatile since was possible carry out numerous reproductible analysis only make the renovation of the paste electrode surface by simple polishing. The sensor was applied successfully in pharmaceutical formulation and river water samples with recoveries percentages near 100%. Electrochemical sensor modified with magnetic nanoparticles coated with MIP and graphene oxide is presented for selective and sensible detection of folic acid in different samples. [Display omitted] •A core@shell MMIP selective towards folic acid was successfully synthesized.•For the first time was using the polyol method to obtain the magnetite core in the MMIP.•The constructed sensor based on carbon/GO paste modified with the MMIP was successful.•The Fe3O4@MIP-GO/CPE sensor was successfully applied in the detection of folic acid with a LOD of 6.5 × 10-7 mol L-1.•Analysis of river water and pharmaceutical formulation reveals the practical applicability of the proposed sensor.