Electrochemical sensor based on graphene and mesoporous TiO2 for the simultaneous determination of trace colourants in food

•We prepare graphene (GN) nanosheets and mesoporous TiO2 (M-TiO2) nanoparticle.•GN is thin and M-TiO2 has continuous ordered mesopores under electron microscope.•GN and M-TiO2 based sensor can simultaneous detect sunset yellow and tartrazine.•Sunset yellow and tartrazine contents in food samples are successfully determined. Currently, synthetic colourants draw much attention as food additives. This paper investigated the simultaneous electrocatalytic oxidation of sunset yellow and tartrazine, two yellow colourants commonly present in food together, with a novel voltammetric sensor based on graphene and mesoporous TiO2 modified carbon paste electrode. Due to the high accumulation effect and great catalytic capability of graphene and mesoporous TiO2, the developed sensor exhibited well-defined and separate square wave voltammetric peaks (i.e., 272mV) for sunset yellow tartrazine. The peak currents of sunset yellow and tartrazine increased linearly with their concentration in the ranges of 0.02–2.05μM and 0.02–1.18μM, respectively. And the detection limit was 6.0 and 8.0nM for sunset yellow and tartrazine, respectively. This new sensor was applied to determine sunset yellow and tartrazine in several food sample extracts. Results suggested that the proposed sensor was sensitive, rapid and reliable.