Electrochemical Sensor for Quercetin Based on the Enhancement Effect of Reduced Graphene Oxide

Graphene oxide (GO) was prepared via chemical oxidation of graphite powder, and then reduced using NaBH4. The resulting reduced graphene oxide (RGO) was dispersed into water and subsequently used to modify the surface of glassy carbon electrode (GCE). The electrochemical oxidation behavior of quercetin was studied. A sensitive oxidation peak at 0.18 V was observed on the RGO film surface in pH 6 phosphate buffer. Compared with the unmodified GCE, the AGO-modified GCE greatly increased the oxidation signal of quercetin. The influences of pH value, amount of RGO, accumulation potential and time were examined on the oxidation peak current of quercetin. Based on the remarkable enhancement effect of RGO, a novel electrochemical method with high sensitivity was developed for the detection of quercetin. The linear range was from 7.5 mu g L-1 to 1 mg L-1, and limit of detection was evaluated to be 3 mu g L-1 after 2-min accumulation. This method was successfully used to determine the content of quercetin in honeysuckle samples, a kind of traditional Chinese medicine. The recovery was over the range from 95.2% to 99.1%.