The Construction Of Electrochemical Sensor Based On Graphene And Its Application For Azo Colors

Graphene has attracted considerable attentions since its first discovery in 2004 as a novel carbon material owing to unique nanostructure of single layer of sp2-bonded carbon atoms. Graphene has shown potential applications in various fields like supercapacitors, batteries, and sensors because it holds so excellent mechanical strength, large specific surface area, and high conductivity. Because of the van der waals force between the graphene slice layers, graphene is easy to reunite and hard to diperse in common solvents. Therefore, some effective methods are needed to functionalize graphene to change its dispersibility and develop its super performance.Nanometal and oxide materials possess fast electron transfer rate and high catalytic efficiency,therefore they show excellent application prospect in the field of optical, electrochemical and catalyst. Nanometal and oxide materials are a kind of important catalysts in organic reactions for their special catalyst size, large specific surface area and many active site basic requirements and so on. Whether they are precious nanometal particles Pt, Pd or ordinary nanometal Co, Ni and ordinary nanometal oxide WO3, they all behave stable and high catalytic activity as usually and were used widely in catalyst field.Food colors are one of the commonly used additives in people’s life, excessive use can be harmful to human health, especially the azo coloes synthesized by organic reaction. Sunset yellow, tartrazine, allura red and amaranth are azo colors that allowed using in food, and their maximum amount must meet the state regulations. Excess use of colors in food will produce bad effect to human body, so we need effective detection and control for the use of food colors.This paper built the sensitive electrochemical sensors of four kinds of azo synthetic colors based on the cationic surfactant CTAB and PDDA functionalization of graphene loaded a variety of nanometal and oxide materials. The synthetic materials were characterized by a variety of methods such as TEM, UV, FT-IR, XRD, EIS and the azo colors were studied by adopting the methods of CV, DPV. These methods were finally applied to the analysis of samples and got good results.1. Determination of sunset yellow in soft drinks based on CTAB-Gr-Pt composite film modified glassy carbon electrodeIn this work,a new and sensitive electrochemical sensor based on CTAB-Gr-Pt composite modified glassy carbon electrode was fabricated via electrostatic self-assembly method. The CTAB-Gr-Pt composite greatly improved the electrochemical signals of sunset yellow, owing to the synergistic effect of the large surface area and electrocatalytic activity of both Gr and Pt NPs. The synthetic materials were characterized by a variety of methods such as TEM, UV, FT-IR and EIS. Cyclic voltammetry(CV) and differential pulse voltammetry(DPV) were used to investigate the electrochemical behavior of sunset yellow. Under the optimized experimental conditions, the linearity range of sunset yellow was 0.08-10.0 μmol/L and the limit of detection(LOD) was 4.2 nmol/L. The developed method showed high sensitivity and was successfully applied to determine sunset yellow in soft drinks with satisfactory recoveries.2. Simultaneous determination of sunset yellow and tartrazine in soft drinks based on PDDA-Gr-Pd composite film modified glassy carbon electrodeIn this work,a novel and sensitive electrochemical sensor was developed based on PDDA-Gr-Pd composite modified glassy carbon electrode. PDDA, acting as a cationic surfactant, strongly connected Pd NPs on the graphene surface. The PDDA-Gr-Pd composite showed good selectivity and high sensitivity to the sunset yellow and tartrazine, which was dependent on the synergistic effect of the large surface area and electrocatalytic activity of both Gr and Pd NPs. The synthetic materials were characterized by a variety of methods such as TEM, UV, XRD and EIS. Meanwhile CV and DPV were used to investigate the electrochemical behavior of sunset yellow and tartrazine. Under the optimized experimental conditions, the linearity range of sunset yellow and tartrazine were 0.01-10.0 μmol/L and 0.01-8.0 μmol/L, respectively. The LOD was 2.0 nmol/L and 5.0 nmol/L for sunset yellow and tartrazine, respectively. The developed sensitive and simple method was successfully applied for simultaneous determination of sunset yellow and tartrazine in soft drinks with satisfactory results.3. Determination of allura red in soft drinks based on PDDA-Gr-Ni composite film modified glassy carbon electrodeIn this section,we fabricated a sensitive electrochemical sensor based on PDDA-Gr-Ni composite modified glassy carbon electrode. The synthetic materials were characterized by a variety of methods such as TEM, UV, XRD and EIS. Meanwhile CV and DPV were used to investigate the electrochemical behavior of allura red. Under the optimized conditions, the linearity range of allura red was 0.05-10.0 μmol/L and the LOD was 8.0 nmol/L. The novel method was applied to determine allura red in soft drinks with satisfactory recoveries.4. Determination of amaranth in soft drinks based on PDDA-Gr-WO3 composite film modified glassy carbon electrodeIn this section,a sensitive electrochemical sensor was successfully prepared based on PDDA-Gr-WO3 composite modified glassy carbon electrode. The synthetic materials were characterized by a variety of methods such as TEM, UV and EIS. Meanwhile CV and DPV were used to investigate the electrochemical behavior of amaranth. Under the optimized conditions, the linearity range of amaranth was 0.01-10.0 μmol/L and the LOD was 6.0 nmol/L. The sensitive method was applied to determine amaranth in soft drinks with satisfactory recoveries.