Highly sensitive and efficient voltammetric method for the determination of 4-aminophenol in paracetamol tablet and urine samples using screen printed carbon electrode modified with humic acid functionalized iron oxide nanoparticles

A simple but very sensitive and selective voltammetric sensor has been investigated for the determination of 4aminophenol (4-A/P) which is based on the screen-printed carbon electrode (SPCE) modified with humic acid functionalized iron oxide nanoparticles (HA-Fe3O4/SPCE). The sensor presented good electrocatalytic performance towards the oxidation of 4-A/P due to the combined conductivity of HA and Fe3O4 nanoparticles on the surface of electrode. The prepared HA coated Fe3O4 nanoparticles were elucidated by Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infra-red (FT-IR). The functional groups in HA on the surface of Fe3O4 nanoparticles acted as mediator that improved the electron transfer rate between the electrode and solution. Using the optimal experimental setup in the solution containing 0.05 M NaH2PO4 at pH 7.5, very sensitive results were achieved between peak currents and concentrations of 4-A/P ranged from 0.025 - 20 mu M with linear correlation coefficient (R2) of 0.997 and the detection limit (LOD) was found to be 6.5 nM. The HA-Fe3O4/SPCE sensor demonstrated selective response for 4-A/P over the other interfering species and exhibited reproducible results with RSD of 3.80 %. The applicability of the proposed method was verified in paracetamol tablet and urine samples which showed good recoveries in the range from 95 % - 101 % (RSD of 1.25) and 95.4 % - 103.4 % (RSD of 2.80), respectively. Thus, the nontoxic and simple HA-Fe3O4 modified SPCE was found to be a suitable electrochemical sensing device for the routine pharmaceuticals and urinary 4-aminaophenol analysis with high sensitivity and selectivity.