Voltammetry sensor based on poly(L-methionine)/reduced graphene oxide/β-cyclodextrin for the simultaneous determination of caffeine, dopamine and serotonin

A novel and cost-effective electrochemical sensor is fabricated for the simultaneous detection of caffeine (CAF), dopamine (DA) and serotonin (ST) in serum samples. The design of an electrochemical sensor is achieved via layer-by-layer modification of a glassy carbon electrode surface (GCE) with poly (L-methionine) (PMT), reduced graphene oxide (RGO) and β-cyclodextrin (CD). The composite is characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and electrochemical impedance spectroscopy. The synergistic interactions between the components significantly improve the overall sensor performance. The anodic current response for CAF increases 3.9 times higher and the potential shifts negatively about – 23 mV compared to GCE. The sensor realizes detection limits as low as 0.067, 0.0311, and 0.038 μM for CAF, DA and ST, respectively. The sensor has good anti-interference capability, repeatability, stability, and reproducibility. The voltammetry method demonstrates excellent recoveries, for precise caffeine quantification in tea, coffee and energy drink samples.