Electrochemical detection of riboflavin in pharmaceutical and food samples using in situ electropolymerized glycine coated pencil graphite electrode

The electronic conductivity and electrocatalytic property of an electrode can be improved by coating its surface with a thin film, polymer or some nanomaterial; however, the fabrication procedure is time-consuming, expen-sive, and require multistep. In this study, an electrochemically polymerized polyglycine-coated pencil graphite electrode (PGl/PGE) was prepared for the sensitive detection of riboflavin (RF). The formation of glycine poly-mer on the PGE surface was confirmed by Fourier transform infrared (FTIR), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), and elemental mapping analysis. The results of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) revealed that the charge transfer on PGl/PGE was significantly enhanced when compared to PGE. The fabricated PGl/PGE sensor was used to detect riboflavin (RF) in 0.2 M phosphate buffer (pH 7.0) using square wave voltammetry. The linear concentration range of RF was 2-450 nM under optimized conditions, with a calculated limit of detection of 1.24 nM. Finally, some critical sensor parameters such as sensitivity, selectivity, stability, and reproducibility were evaluated and practically applied for RF detection in pharmaceutical and food samples.