Preparation of Novel Cystine-multiwalled Carbon Nanotubes-graphene Oxide-glassy Carbon Electrode and Electrochemical Detection of Riboflavin and Dopamine

摘要

A glassy carbon electrode (GCE) was used as a substrate, and cystine (Cys), carboxylated multiwalled carbon nanotubes (MWNTs), and graphene oxide (GO) were ultrasonically mixed. The surface of the GCE was modified, and a Cys-MWNTs-GO-GCE-modified electrode was prepared. Scanning electron microscopy was conducted to characterize the surface morphology of Cys-MWNTs-GO, which had a loose and porous structure. The electrochemical properties of the modified electrode were examined using K-3[Fe(CN)(6)], and the calculated electrode area of Cys-MWNTs-GO-GCE was 7.0397 x 10(-6) cm(2) . Results also showed that the maximum amperometric response of the modified electrode was reached when the pH values of phosphate-buffered saline for vitamin B-2 (VB2) and dopamine (DA) were 6.60 and 7.00, respectively. The modified electrode could detect VB2 and DA in the linear concentration ranges of 2.0 x 10(-9) -3.0 x 10(-4) and 1.3 x 10(-8) -2.5 x 10(-4) mol/L, respectively. Linear equations could be described as follows: I-p((VB2)) = 4.6149 + 4.9889c and I-p(DA) = 3.0063 + 1.8508c. The detection limits of VB2 and DA were 1.2 x 10(-9) and 1.0 x 10(-9) mol/L, respectively (S/N = 3). These results demonstrated the high stability and reproducibility of the detection method with a peak current of RSD = 1.37%. The developed method could be applied to determine the contents of VB2 and DA in urine and blood samples, respectively.