The Analytical Application Research Of Stripping Voltammetry With Composite Mercury Film Electrode For Environment And Food

The content of trace elements has great relation to human health.The determination of trace elements plays an important role in the essay of environmental science,medicine,food and clinic.The chemically modified electrode(CME) has been one of the most flourish research realms in the electrochemistry and electroanalytical chemistry since it was developed in the 1970th.Among various of modified materials used to fabricate chemically modified electrode,polynuclear metal hexacyanometallate have been extensive studies for the applications in electrocatalysis,electrochemical sensors,functional materials,molecular sieves, solid-state batteries and molecular magnetism due to their good chemical and electrochemical stability,profuse electrochemical activities.Combined analogue of prussian blue modified electrode and the traditional advantages of mercury film electrode,this thesis studies the preparation and electroanalytical application of the modified PB-Eu composite mercury film electrode(PB-Eu/MFE) on glass carbon substrate.The PB-Eu/MFE has successfully apply to determine trace levels of bismuth,copper,lead,cadmium and vitamin B₂ in environmental samples by differential pulse stripping voltammetry.The PB-Eu/MFE remarkably shows higher sensitivity,perfect stability,long-lived and good date repeatability and also more and more potential application in the field of electroanalysis future and satisfactory results are obtained.The main researches are summarized as follows:Chapter One ReviewThe first section has reviewed the history,current situation and future trend of composite mercury film.The preparation and application of chemically modified composite mercury film electrode are introduced simply.In the second section,the type and application of stripping voltammetry are summarized in detail,paying attention to anodic stripping voltammetry and cathodic stripping voltammetry.The present application researches of anodic stripping voltammetry in analysis of environmental samples are introduced in the third section.The fourth section summarizes the vitamins feature in food and pays more attention to the determination of using water-solubility vitamins matters electrochemical methods.At last,the purpose and meaning of this work are discussed.Totally 100 references are cited in the chapter one.Chapter Two Determination of adhesive lead(â…¡) of leaves in city using anodic stripping voltammetry with composite mercury film electrodeAdhesive lead(â…¡) of leaves in city is determined by differential pulse anodic stripping voltammetry and the main causation that made tree contaminated is deduced by the experimental data.The results reveals that a stripping peak potential of lead is observed at -0.472 V(vs.SCE) in 0.01 mol/L HNO₃ using the PB-Eu composite mercury film electrode as working electrode.Under the optimum conditions,good linearity is obtained in the concentration range of 2.4～300μg/L(r=0.9991,n=11) with a detection limit of 0.2μg/L(S/N=3) and RSD is 1.35%.This method is used for the determination of lead adhered to the surface of leaves,which is sampled in three different locals of Lanzhou city.The recoveries of the method are 97.3%-102%.The results showed that the lead pollution on tree leaves is from automobile tail-gas mainly and its lead content is positively correlative with the traffic presented on city streets near the tree.Chapter Three Determination of bismuth,copper,lead and cadmium of waste dry batteries using anodic stripping voltammetry with composite mercury film electrodeA PB-Eu composite mercury film electrode is developed for simultaneous determination bismuth,copper,lead and cadmium of waste dry batteries by differential pulse anodic stripping voltammetry.The results reveals that stripping peak potentials of bismuth,copper,lead and cadmium are observed at -0.21 V,-0.34 V,-0.55 V,-0.75 V(vs.SCE) in 1 M KCl-10%lactic acid using the PB-Eu composite mercury film electrode as working electrode.Under the optimum conditions,the method has good linearity in the ranges of 4.0～160μg/L for bismuth(r=0.9986,n=8), 2.0～160μg/L for copper(r=0.9992,n=8),2.0～240μg/L for lead(r=0.9990,n=8)and 8.0～360μg/L for cadmium(r=0.9989,n=8);detection limits are 0.4μg/L,0.4μg/L, 0.2μg/L and 0.6μg/L(S/N=3);RSD are 3.80%,3.61%,2.37%and 3.88%for bismuth, copper,lead and cadmium,respectively.This method is used for the simultaneous determinations of bismuth,copper,lead and cadmium of waste dry batteries,the recoveries of the method are 97.4%-103%.The results show that the advantages of this method are simple and fast,its operation is stable and reliable,it is applied to simultaneous determination of these elements in waste dry batteries samples with satisfactory results.Chapter Four Determination of VB₂ in tablets and soft beverage using cathodic adsorptive stripping voltammetry with composite mercury film electrodeVB₂ in tablets and soft beverage is determined by differential pulse adsorptive cathodic stripping voltammetry with composite mercury film electrode.The results reveal that an adsorptive stripping peak potential of VB₂ is observed about -0.25 V (vs.SCE) in 0.04mol/L KCl-0.01mol/L HNO₃ support electrolyte.Under the optimum conditions,good linearity is obtained in the concentration range of 16～1600μg/L(r=0.9989,n=9) with a detection limit of 1.2μg/L(S/N=3) and RSD of 1.58%. This method is used for the determination of VB₂ in tablets and soft beverage.The satisfactory results are obtained.