Studies On Analytical Detection Of Heavy Metal Cadmium Ions

Since the 21st century,many aspects of society have been developing rapidly,and the national living standard has been greatly improved.In the world,especially in China,such as cadmium,lead,mercury,chromium and other heavy metal ions have caused serious pollution in our surrounding environment,which has brought a very big threat to people’s health and even life.When the content is very low,these heavy metals enter the water and have the poisonous effect on the aquatic organism.What’s worse,the pollution which was caused by these heavy metals is irreversible,widespread and covert,and the complex compounds formed with a variety of substances can evade some conventional detection methods.Therefore,the rapid and quantitative detection of trace heavy metals in the field of environment,medicine and food has aroused great attention of the state,and it is urgent to establish sensitive,rapid and specific heavy metal detection methods.In this paper,the surface plasmon resonance competition immunoassay and functionalized gold nanoparticles were established to detect the cadmium heavy metal ions of heavy metals.The details are as follows:First of all,we briefly introduce some of the related summarization of heavy metals and certain methods of heavy metal detection in the first chapter.Second,the main work of this experiment is to use the dual function reagent phenyl isothiocyanate–EDTA（ITCBE）obtain the immunogenicity of cadmium ions,then obtain the monoclonal antibodies against cadmium ions by using cell fusion and hybridoma technology,combining with real-time,label-free surface plasmon resonance（SPR）technique to establish a new Immunoassay method for detecting cadmium heavy metal ions.At the beginning,we discussed the influence of antigen concentration,buffer solution pH and flow rate on SPR signal intensity and experiment.And we determined the best antigen concentration,buffer pH and solution flow rate.Then,under the optimal conditions,a series of different cadmium ions concentrations 0,1,10,20,50,100,200,500,1000 ng/mL were measured,and the IC₅₀standard curve of cadmium ions under different concentrations was established based on SPR,and the IC₅₀ of the method was 23.58 ng/mL and the detection limit was 1.25 ng/mL.Subsequently,the cross-reactivity of heavy metal ions Hg²⁺,Cu²⁺,Ni²⁺,Co²⁺,Cr³⁺,Pb²⁺,Mg²⁺and Zn²⁺respectively was detected.Finally,the practical application of the proposed biosensor was evaluated in samples which were collected from Wenying lake and our laboratory tap water,and the recovery rate at the concentration of 10,20,50 ng/mL are determined.Third,a functionalized gold nanoparticle was developed to detect cadmium ions in aqueous solution in the third chapter.The effects of the solution pH value,concentration of mercapto propionic acid（MPA）and L-Cystine were explored further to the experimental,the optimal experimental conditions were determined,and a functionalized gold nanoparticles with good properties were prepared.The cadmium ions solution with 10^-9–10^-4 mol/L concentration were detected in the real aqueous samples,the recovery rate of the functionalized Au nanoparticles for Cd²⁺in water samples was 94.00%¹03.00%.Finally,in the fourth chapter,we briefly summarized and generalized this paper,and hope to provide some reference for the future research work.