| As research continues, Rare Earth Elements have found an increasingly wide utilization in allfields. Especially in recent years, much attention was attached to their application in agriculture.Research has shown that many plants are rich in rare earth elements, and REE is a stimulus togrowth of plants and increase its resistance, even increase crop yields. The Gannan area of Jiangxiprovince was known as the Kingdom of rare earths, its soil is an excellent source of REE absorbedeasily by plants. There are reports indicate that the reason why Gannan navel oranges quite sweetand juicy is related to its rich REE in soil. So, to know the content of REE in soil has a vitalsignificance in understanding crop growth status, nutritional status of the soil, and thus thedetermination of trace rare earth elements in soil is also very important.Several Analysis methods can be used for testing the content of REE, the main one isInductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) which has high sensitivity,low detection limit, wide linear range of advantages. It is widely used. However, the complexemission spectra from high excitation energy of ICP and interference spectral of Partial REE’becomes a problem puzzled analyst. Especially in the determination of trace levels of REE withincomplicated matrix samples like soil, matrix interference is another problem. Therefore, toestablish a method with effective pretreatment of soil for detecting the REE accurately byICP-AES has practical significance to extending the application of ICP-AES in the analysis oftrace rare earth elements in soil.An effective method for detecting the trace rare earth elements in soil by ICP-AES has beenestablished in present paper. The spectral interference between REE and the condition of soildigestion, the separation and enrichment of REE have been researched. The potential of themethod was evaluated by the determination of REE in standard reference materials. The methodestablished in present work is simple，quick and can adapt to multiple samples analysis. It reducesthe loss of the process to improve the accuracy of the experimental results effectively and extendsthe application of ICP-AES in the analysis of trace rare earth elements in soil. This research willhave practical significance for the study of trace REE content in soil and for its potentialagricultural value. Full Text briefly as follows:Chapter one: a brief overview about rare earth elements and its detection method wasintroduced. The purpose and significance of this research was also described.Chapter two: The spectral interferences of rare earth elements were researched and the type ofspectral interference between rare earth elements is explained. In this chapter, a methodeffectively remove or reduce spectral interference on optimized analytical line was proposed. Theresults show that the optimized analytical lines of Partial REEs are Dy:353.170nm/340.780nm,Er337.271/390.631/349.910, Tm313.126nm/346.220, Ho345.600nm/389.102nm/351.559nm,Pr418.948nm/406.281nm. The others’ REE analysis lines are: La:379.478nm,Ce:413.765nm/418.600nm, Nd406.109nm, Eu:381.967nm/412.970, Gd:342.247nm, Tb:365.888nm, Yb:328.937nm, Lu:261.542nm, Y:371.030nm.Chapter three: The condition of soil samples pre-treatment were optimized, including theconditions of microwave digestion, digestion reagents, the process of precipitation separation, etc.The results show that soil digested with mixture acid of HNO3, HF, HCl and EDTA by MicrowaveAccelerated Reaction System is very efficacious and the REEs in soil separated and enrichedsuccessively by NaOH and NH3H2O are also effective. Chapter4: The method was evaluated by the determination of REEs in standard referencematerials (GSS-4，GSS-5). The results agreed well with the certified values. The recoveries werein the range of90%-110%indicating that the method is accurate and reliable. The method can besuccessfully applied to detect the actual soil samples from Gannan navel orange orchard. |
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