The Study Of Fluorescence Determination For Rare Earth Element Yttrium、Ytterbium And Neodymium

Rare Earth elements were important strategic elements,and they were widely used in petroleum,chemical industry,metallurgy,ceramics,textile,glass,materials and other different fields.With the development and utilization of rare earth elements,it was inevitable to enter the environment,food chain and organisms through various channels.Therefore,it was of great significance to study the determination of rare earth elements.Fluorescence spectrophotometry has been widely used in the determination of trace elements because of its high sensitivity,low detection limit,good selectivity and simple operation.The fluorimetric determinations of rare earth elements yttrium,ytterbium,neodymium were studied in the paper.And the main points were as follows:1.Some new methods of fluorescence analysis and their applications are introduced.The application of fluorescence analysis is reviewed,and the application of other methods in rare earth elements is reviewed.The application prospect of fluorescence analysis for the determination of rare earth elements is prospected.2.It was found that trace yttrium（III）had a good catalytic effect on the reaction about hydrogen peroxide oxidation Wright’s stain,and a new Catalytic kinetic fluorescence spectrophotometric method for the determination of trace amounts of yttrium（III）was proposed.In this paper,the spectral characteristics of the fluorescence system was investigated,and such influence factors on the reaction were discussed as the influence of reagent amount,acidity,reaction temperature,reaction time and coexisting ions,and the optimum reaction conditions were also determined.Experiments results indicated that the maximum excitation（λex）and the emission wavelength（λem）of the system were 512 and 538nm respectively.The proposed method was allowed to determine yttrium in the range of 0.2-1.8μg·m L^-1with good precision and accuracy.The detection limit was 3.97×10^-3μg·m L^-1.The equation of linear regression isΔF=12.4547ρ+5.5761,and the coefficient of correlation was 0.9973.In this experiment,the content of yttrium in cerium acetate was determined,and the recovery rate was between 92.5%and 104.3%,and the relative standard deviation was between 1.5%and 2.2%.3.In H₃BO₃-Na₂B₄O₇buffer solution,fluorescein can emit strong fluorescence spectra at specific excitation wavelength,and the fluorescence intensity of the system decreases with the addition of trace ytterbium ion.A new fluorescence spectrophotometric method for the determination of ytterbium was developed based on the linear relationship between the fluorescence intensity variationΔF and the ytterbium in a certain concentration range.The effects of acidity,surfactants,the amount of fluorescein,the order of reagents,reaction temperature,reaction time and the influence of coexisting ions were investigated in this paper.The experimental results show,it has a good linear relationship with the change amount of fluorescence intensity that the concentration of ytterbium（III）in the range of 0.2～2.0μg·m L^-1.The equation of linear regression isΔF=25.9967ρ-0.2651,the detection limit is 1.14×10^-3μg·m L^-1,and the correlation coefficient is 0.9986.The content of ytterbium in the sample was determined by this experiment.The recovery rate of the added standard was between 97.5%and 106%.4.Pyronin B itself has a strong fluorescence,and the maximum excitation wavelength is 529 nm,the maximum emission wavelength is 549 nm,The fluorescence intensity of the solution was enhanced after adding the surfactant cetylpyridinium bromide（CPB）,but the shape of the fluorescence spectrum of the system did not change.The fluorescence intensity of the system was further enhanced after the addition of neodymium ion in the above solution,and a new system for the determination of trace neodymium by fluorescence spectrophotometry was established.The effects of acidity,the selection and dosage of surfactant,the dosage of pyronin B,the reaction temperature,the reaction time and the interference ions on the fluorescence intensity were investigated,and the optimum conditions of the experiment were determined.It is found that under the selected experimental conditions,when the concentration of neodymium ion is in the range of 2～16μg·m L^-1,there is a good linear relationship betweenΔF and the concentration of neodymium ion.The equation of linear regression isΔF=3.5133ρ+2.8540,and the correlation coefficient is 0.9982.The detection limit of this method is 1.13×10^-2μg·m L^-1.The method has been applied to the determination of trace neodymium in the sample,and the recovery rate is 92.8-105.4%.