Electrochemical Sensors Based On Novel Nanocomposite And Its Application In Analysis Harmful Substances Of Chinese Medicine

With the advantages of fast response,convenience,sensitivity,low cost,simple pretreatment and application in online analysis,electrochemical sensors a pivotal technology in the field of analysis and detection,mainly used in environmental protection,medical monitoring,food and drug safety.In recent years,Superior Performance Nanomaterials are the key for the development of chemically modified electrodes,which have been widely used in the field of sensors Nanomaterials such as graphene,carbon nanotubes and metals have become a research hotspot in many fields due to unique space structure their good electrocatalytic ability.Therefore,the construction of novel nanocomposites is the current research trend in the field of electrochemical sensors.In this paper,based on the characteristics of some materials,several electrode nanocomposite-modified were constructed and applied to the accurate and sensitive detection of harmfuL substances in Chinese medicines.The research and investigation contents of this dissertation can be summarized as the following three parts:?1?Preparation of Mg-Al-LDH/p-m-ABSA modified glassy carbon electrode and its electrochemical behavior to methyl parathion and fenitrothionIn the experiment,the glass carbon electrode modified by poly-m-aminobenzene suLfonic acid film was prepared by puLse potential electropolymerization.The composite modified electrode?Mg-Al-LDH/p-m-ABSA/GCE?was prepared by coating appropriate amount of Mg-Al bimetallic hydroxides onto the surface of the modified electrode in combination with p-m-ABSA to obtain a composite modified electrode?p-m-ABSA/GCE?.The surface morphology and effective area of the sensor electrode were characterized by scanning electron microscopy?SEM?:energy dispersive spectroscopy?EDS?and electrochemical methods.And the electrochemical behavior of methyl parathion and fenitrothion on the modified electrode was also studied.The resuLts performed that Mg-Al-LDH/p-m-ABSA/GCE had good electrocatalytic performance for methyl parathion and fenitrothion.After optimizing the experimental conditions,under the optimum conditions,the oxidation peak current of methyl parathion showed a good linear relationship with its concentration in the range of 0.1?M to 20.0?M,r was-0.9983,the detection limit LOD was 33.0 nM?S/N=3?;the oxidation peak current and concentration of fenitrothion showed good linear relationship with its concentration in the range of 0.01 to 5.0?M and 5.0 to 60.0?M,respectively,r was-0.9936 and-0.9927,respectively.The reduction peak current and concentration showed a good linear relationship with its concentration in the range of 5.0 to 60.0?M,r was-0.9881,and the detection limit LOD of fenitrothion was 3.5 nM?S/N=3?.The modified electrode can be successfuLly applied to the analysis and detection of methyl parathion and fenitrothion in Magnolia officinalis and Scutellaria baicalensis with satisfactory resuLts.?2?Anodic stripping electrochemical behavior of Pb²⁺,Cd²⁺,Cu²⁺,Hg²⁺on ILS-Mg-Al-LDH modified activated glassy carbon electrode and simuLtaneous analysis anddetectionThe performance of magnesium-aluminium bimetallic hydroxides?Mg-Al-LDH?was optimized by ionic liquids?ILS?:and the ILS-Mg-Al-LDH dispersion was obtained.ILS-Mg-Al-LDH was modified to a bare glassy carbon electrode activated by dilute suLfuric acid to prepare ILS-Mg-Al-LDH/GCE.The modified electrode was applied to the simuLtaneous determination of four common heavy metal ions,Pb²⁺,Cd²⁺,Cu²⁺,Hg²⁺.The experimental conditions,such as modification concentration,deposition time,deposition voltage and buffer pH,which affect the analysis and detection effects of Pb²⁺,Cd²⁺,Cu²⁺,Hg²⁺were optimized.Under the optimum conditions,Pb²⁺,Cd²⁺,Cu²⁺,Hg²⁺were analyzed simuLtaneously.The linear relationship between Pb²⁺and Cu²⁺was good in the range of 0.05 to 4.0?g·L^-1,r was 0.9956 and 0.9933,the detection limits of LOD were 16.0 ng·L^-1 and 25.0 ng·L^-1?LOD S/N=3?repectively.And the linear relationship between Cd²⁺and Hg²⁺was well in the range of 0.5 to 50.0?g·L^-1,r was 0.9967 and 0.993,the detection limits of LOD were 0.25 and 0.18?g·L^-1?S/N=3?respectively.The resuLts illustrate that ILS-Mg-Al-LDH/GCE can simuLtaneously detect and separate Pb²⁺,Cd²⁺,Cu²⁺,Hg²⁺at low concentration.The method can be successfuLly used for the analysis of Pb²⁺,Cd²⁺,Cu²⁺,Hg²⁺in orange peel and tea samples.?3?Determination of carbendazim in lithospermum and glycyrrhiza uralensis using a electropolymerized L-cysteine-?-cyclodextrin modified glassy carbon electrodeIn the experiment,a facile and novel poly?L-cysteine-?-cyclodextrin?modified glassy carbon electrode was prepared.And the surface morphology of the modified electrode was characterized by scanning electron microscopy?SEM?and energy dispersive spectroscopy?EDS?.The electrochemical behavior of carbendazim on the modified electrode was investigated.The experimental conditions of poly-L-cysteine-?-cyclodextrin polymerization,scanning rate,buffer pH and other conditions were investigated.The resuLts show that polyL-cysteine-beta-cyclodextrin has excellent electrocatalytic ability,which can significantly improve the peak current of Carbendazim and promote the electrochemical response on the electrode surface.After optimizing the conditions affecting carbendazim,the reduction peak currents of carbendazim show a good linear relationship in the range of 0.05 to10.0?M and10.0 to 75.0?M,respectively.The detection limits of r were 0.9976 and 0.9931with LOD of 18.0 nM?S/N=3?.The method can be successfuLly applied to the detection and analysis of carbendazim in lithospermum and licorice.