Preparation of yolk–shell structured copper oxide@silica oxide spheres and their application in high performance electrochemical sensing of Formoterol fumarate residues in swine feed and tissues

In this paper, we report a facile route to synthesize yolk–shell structured copper oxide@silica oxide (CuO@SiO 2 ) spheres and their application to construct an electrochemical Formoterol fumarate (FF) sensor. The CuO@SiO 2 was characterized by means of Fourier transform infrared spectroscopy, X-ray powder diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. Further, FF was electrocatalytically oxidized at the CuO@SiO 2 film modified glassy carbon electrode (GCE), which led to a sensitive determination of FF. The oxidation current of FF was linear with concentration in the range of 0.030–10   μM and the detection limit was found to be 5.0   nM (S/N   =   3). The observed analytical parameters such as wide linear range, low detection limit and short response time were superior to previously reported FF sensors. Finally, it was demonstrated that the proposed sensor could be used for the selective determination of FF present in swine feed and tissues.