Fabrication of gadolinium decorated spherical zinc oxide attached on carbon nanotubes (Gd@ZnO-MWCNTs) for electrochemical detection of a bisphenol derivative BPSIP in real sample matrices

In this study, we have developed a reliable electrochemical sensing platform for determining the residue of 4-(4-iso-propoxy-benzenesulfonyl)-phenol (BPSIP), an endocrine disruptor in blood serum, plastic and paper samples. A wide concentration range of BPSIP was electrochemically determined for the first time on glassy carbon electrode modified with newly developed gadolinium doped zinc oxide-multiwalled carbon nanotubes nanocomposite (Gd@ZnO-MWCNTs/GCE). The Gd@ZnO-MWCNTs nanocomposite was prepared by simple procedure through stirring under reflux condition and was characterized by several physicochemical techniques such as Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray analysis (EDAX), and X-ray photoelectron spectroscopy (XPS). The electrochemical activity of the prepared nanocomposite was investigated by the differential pulse voltammetry (DPV). It was observed that Gd@ZnO-MWCNTs/GCE exhibits lower oxidation potential toward oxidation of BPSIP due to its fast electron transfer capability and high conductivity. A wide linear concentration ranges from 0.5 to 80 mu M was attained with LOD of 0.2 mu M. The sensitivities were found to be 26.33 mu A mM(-1)and 14.89 mu A mM(-1) in two successive concentration ranges. The kinetic studies were also performed by employing chronoamperometry in the presence of BPSIP at Gd@ZnO-MWCNTs/GCE that exhibits catalytic rate constant (k(cat)) of 7.54 x 10(2) M-1 s(-1) and the diffusion coefficient (D) of 1.56 x 10(-5) cm(2)s(-1). Further, the fabricated Gd@ZnO-MWCNTs/GCE has shown excellent reproducibility with resultant RSD of 0.21% and storage stability of 21 days with 86% retention in current. [GRAPHICAL ABSTARCT]