Direct preparation of well-dispersed graphene/gold nanorod composites and their application in electrochemical sensors for determination of ractopamine

Well-dispersed graphene/gold nanorod (G/GNR) composites were synthesized by directly reducing a mixture of graphene and gold growth solution with sodium borohydride. The synthesized G/GNR composites were characterized by ultraviolet-visible spectroscopy and Fourier transform infrared spectroscopy, and the composites were observed by transmission electronic microscopy, which revealed that the GNRs were self-assembled onto the surface of graphene sheets. Glassy carbon electrodes were modified with G/GNR composites to construct a ractopamine electrochemical sensor. A sensitive, rapid, and simple electrochemical method was developed for the detection of ractopamine based on the strong enhancement effect of G/GNRs. The peak currents varied linearly with the concentration of ractopamine over the range of 1 × 10−9 to 2.7 × 10−6 mol L−1, and the detection limit was 5.1 × 10−10 mol L−1 (S/N = 3). This method was applied to detect the content of ractopamine in swine urine samples, and the recovery was in the range of 99.2 to 107.3%.