Construction Of Electrochemical Sensor Based On Three Kind Of Nanocomposite Materials And Its Application In Food Detection

In recent years,nanocomposite materials have received widespread attention.Nanocomposites are formed by two or more substances through physical or chemical action.In addition to maintaining the properties of each component,it can also exhibit properties that each component does not have when it exists alone.A new type of functional material.It has the advantages of large specific surface area and nano-size effect,compound synergistic multifunctional effect,relatively good thermal and chemical stability,and improved electrocatalytic activity and selectivity for the detection of target analytes.Therefore,it is used in electrochemistry the sensor plays a very important role.In this paper,based on carbon nanomaterials,organic compounds,metal-organic frameworks and their derivatives,nanocomposites with different functions are synthesized to construct three sensing interfaces,which realizes the detection of some specific ingredients in food,food additives,and hormone analogs.Highly sensitive detection.The research content of this article is mainly divided into the following three aspects:（1）The nickel-based metal organic framework（Ni-BTC）is synthesized by hydrothermal synthesis using nickel nitrate and 1,3,5-benzenetricarboxylic acid,and then the nickel nanoparticles/nitrogen-doped carbon nanosheets are synthesized by the next step of calcination in a nitrogen atmosphere.The nickel nanoparticles/nitrogen-doped carbon nanosheets and chitosan are used to prepare nanocomposite materials to modify glassy carbon electrodes by ultrasound.Based on this,an electrochemical sensor was constructed for sensitive detection of bisphenol A.The preparation process of the modified electrode was analyzed by scanning electron microscopy and electrochemical impedance spectroscopy and other characterization methods,and bisphenol A was detected by differential pulse voltammetry.The results show that the nickel nanoparticles/nitrogen-doped carbon nanosheets/chitosan/glassy carbon electrode has a large specific surface area,catalytic activity and anti-pollution ability,and realizes the sensitive and selective determination of bisphenol A with a detection limit of 45 n M,and successfully applied to the detection in actual samples.（2）First,acidify the multi-walled carbon nanotubes,and then ultrasonically prepare anthraquinone（AQ）/multi-walled carbon nanotubes（MWCNT）/chitosan（CS）nanocomposites with anthraquinone and chitosan.Therefore,a dual-rate electrochemical sensor for detecting propyl gallate（PG）was constructed.In the presence of the analyte propyl gallate,the anthraquinone/multi-walled carbon nanotube/chitosan/glassy carbon electrode has three oxidation current peaks at different potentials.These three current peaks are respectively related to the electrooxidation of propyl gallate,anthraquinone and multi-walled carbon nanotubes.Among them,anthraquinone and multi-walled carbon nanotubes can be used as internal reference electroactive probes.The results show that anthraquinone,acidified multi-walled carbon nanotubes and chitosan modified glassy carbon electrode can enhance the electrochemical signal of propyl gallate,thereby improving the detection sensitivity of propyl gallate.In the range of 1.0-30.0μM,the ratio signals of I_PG/I_AQ and I_PG/I_MWCNT both increased linearly with the increase of propyl gallate concentration,and the detection limits were 0.67μM and 0.76μM,respectively.The electrochemical sensor can be used for the detection of propyl gallate in edible oil with satisfactory results.（3）Using nickel nitrate and terephthalic acid to synthesize nickel-based metal organic framework（Ni-PTA）by hydrothermal synthesis,and then ultrasonically composite with methylene blue（MB）,drop the above composite dispersion on the electrode and conduct electropolymerization.The electrode was modified to construct a ratio electrochemical sensor for sensitive detection of caffeic acid（CAE）.Polymethylene blue（PMB）@nickel-based metal organic framework nanocomposite has a large specific surface area and high electrocatalytic ability,which helps to improve the sensitivity of detecting caffeic acid and enhance the electrochemical signal of the internal reference probe polymethylene blue.As the concentration of caffeic acid increases,the peak oxidation current of caffeic acid increases,while the peak oxidation current of polymethylene blue remains almost unchanged.The ratio of the net peak current of caffeic acid to polymethylene blue is used as the output signal for the quantitative detection of caffeic acid content.The experimental results show that the linear range is 0.25-15μM,and the detection limit is 0.2μM.On the other hand,when the sensor is used for the determination of the total polyphenol content in the actual chrysanthemum tea,it can be comparable to the traditional Folin-Ciocalteu spectrophotometry.