Eco-friendly synthesis of aloe vera plant extract decorated iron tungstate nanorods immobilized Nafion for selective and sensitive determination of theophylline in blood serum, black tea and urine samples

This paper describes a selective and sensitive detection of bronchodilators (theophylline) using an aloe vera plant extract decorated iron tungstate nanorods (AFW) immobilized Nafion (Nf) modified glassy carbon electrode (GCE) (AFW/Nf/GCE). The AFW was synthesized by the co-precipitation method and characterized by UV-visible spectroscopy, x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), elemental analysis (EDX) and electrochemical studies. Interestingly, the oxidation of theophylline with AFW/Nf/GCE displayed a superior electrocatalytic activity as compared to bare GCE and iron tungstate (FW) modified GCE. The oxidation of theophylline in an electrochemical sensor also revealed a linear current response range from 0.1 to 160 mu M and a low detection limit (LOD) of 0.0028 mu M. This sensor showed high selectivity, stability and reproducibility to tested biological and food samples. It has been successfully applied for the selective determination of theophylline in human serum, black tea, and urine samples. (C) 2019 The Authors. Publishing services by Elsevier B.V. on behalf of Vietnam National University, Hanoi.