Synthesis Of Rare Earth Nanoparticles And Analytical Applications Of Rare Earth Ions In Pharmaceuticals And Foods

As a new material for the 21st century, nanomaterials have been attracting wide attention from researchers owing to its unique physical and chemical properties and have been widely used in electronic, optical, chemical, ceramics and medicine. Rare earth elements have many unique properties. For example, there are many unpaired electrons in the inner 4f electron shell and results in high atomic magnetic moment. Rare earth elements electron energy level transition number are 1-3 orders of magnitude more than others in periodic table and results in electron energy-rich. In addition rare earth elements can form compounds with multivalent and multi-coordinationnumber (from 3-12) because it was easy to lose their valence electron. Rare earth nanomaterials have many special properties, such as small size effects, high specific surface effects, quantum effects, strong optical, electronic, magnetic properties, superconductivity and high chemical activities. Rare earth nanomaterials play an important role in luminescent materials, magnetic materials, electronics materials, ceramics materials and catalysts.LaF₃ was used widely as an ideal luminescient host material. It has low phonon energy and can minimize the quenching of rare-earth ions in the excited state, resulting in high fluorescence quantum yield. It was also used in the fields of lubricant additives, hydrogen storage alloy, chemical sensors, electrode materials etc. Many synthesis methods of nanomaterials about LaF₃ and LaF₃:Ln³⁺ were developed since Asprey LB first reported LaF₃ crystal data in 1957. In this paper, we presented a simple method for the preparation of LaF₃ and LaF₃:Eu³⁺ nanoparticles, and explored the application of rare earth ions in pharmaceuticals and foods. (1) LaF₃ nanoparticles were prepared via precipitation of rare-earth trifluoride at room temperature with the presence of cetyltrimethylamrnonium bromide (CTAB). Structure and properties of the nanocrystals were characterized by means of scanning electron microscope, powder X-ray diffraction and fluorescence spectrophotometer. The nanoparticles are of plate shape. Its diameter is about 45 nm. The obtained nanoparticles have excellent crystallization property. The influencing factors such as reaction temperature, stirring speed, reaction time, dropping acceleration, amount of surfactant on the size and morphology of nanoparticle were investigated. Meanwhile, the LaF₃:Eu³⁺ nanoplates were prepared in the optimum conditions. The effects of Eu³⁺ on the luminescence intensity of LaF₃:Eu³⁺ nanodisks were investigated. The fluorescence lifetime of LaF₃:Eu³⁺ nanodisk is 3.89 ms.(2) A resonance light scattering (RLS) detection method for adenosine disodium triphosphate (ATP) was developed based on the enhancement of RLS signals of ATP by cerium ions in alkalescent aqueous medium. The enhanced RLS intensities were proportional to ATP content over the range of 2.0-18μmol/L with a LOD of 51.3 nmol/L. An adenosine triphosphate combined two cerium ions in terms of the Scatchard law. The method has been applied to determination ATP in injection samples with a recovery range of 94.96% -103.98%. RSD is less than 2.3%.(3) In acidic conditions, it was found that the intensity of fluorescence and resonance light scattering (RLS) was enhanced by interaction between europium ion and sodium hexametaphosphate, while no such phenomenon can be observed to other simple phosphates. The optimum condition, binding ratio and spectral characteristics of complex were investigated. The fluorescence lifetimes of europium ion have been measured before and after interaction. The enhanced fluorescence intensities were proportional to SHMP content in a certain range. Hereby, we developed an enhancement fluorescence method to determinate SHMP. The linear range is 4.0 - 16 umol/L with a LOD of 0.34 umol/L. The method was applied to determination SHMP in tea drinks with a recovery range of 96.7%-109.4%. RSD is less than 3.0%.