New insight for simultaneous detection of methocarbamol and paracetamol in human serum samples based on poly(L-methionine)/graphene-graphene oxide nanocomposite

A new insight is presented for simultaneous detection of methocarbamol (MET), and paracetamol (PAR), in human serum samples. The design of an electrochemical sensor is achieved by modifying the surface of a glassy carbon electrode (GCE) with two successive thin films from conductive poly(L-methionine) (PMT) and a mixture of reduced graphene oxide and graphene oxide (RGO-GO). The composite is characterized by scanning electron microscopy (SEM), atomic force microscope (AFM), and Fourier transform infrared spectroscopy (FT-IR). The sensor creates a powerful sensing platform for MET and PAR detection with kinetically enhanced oxidation process. An increase in the anodic current responses for MET and PAR is obtained with 10.1 and 5.9 times higher compared to bare GC electrode, respectively. Mixing GO with RGO increases the surface area, and the reactive sites due to presence of oxygen-functional groups at its surface. The sensor has good stability, repeatability, reproducibility, and anti-interference capability. The detection limits are 5.2 nM and 1.2 nM for the determination of MET and PAR simultaneously in serum sample in the concentration range (0.04 -> 100 mu M). Large peak potential separation between the MET and PAR about 822 mV is attained. The assay of drugs in serum samples and pharmaceutical formulations is successfully achieved with good recovery values.