Highly sensitive determination of Orange II based on the dual amplified electrochemical signal of graphene and mesoporous TiO2

Orange II, an azo dye, is not permitted in food preparations as it can cause many adverse health effects when consumed. Therefore, the monitoring of Orange II is quite important. Herein, an electrochemical method for the sensitive and rapid analysis of Orange II was reported using mesoporous TiO2 decorated graphene nanocomposite as the sensing film. In pH 4.4 HAc-NaAc buffer, an irreversible oxidation peak at 0.68 V was observed for Orange II. Compared to the unmodified electrode, the graphene-mesoporous TiO2 modified electrode remarkably increased the oxidation signal of Orange II. The detection conditions such as pH value, amount of modifier, accumulation potential and time were optimized and the electrochemical reaction mechanism of Orange II was discussed. The limit of detection for Orange II is 0.92 nM. Finally, the new method was successfully employed to detect Orange II in chilli products and ketchup samples, and the results were tested by high performance liquid chromatography-tandem mass spectrometry.