Analytical Sciences

Determination of Rare Earth Elements in Geological Samples by Inductively Coupled Plasma Atomic Emission Spectrometry with Flow Injection Liquid-Liquid Extraction

Zhifang XU,*  Congqiang LIU,** Hongxiang ZHANG,* Yingjun MA,* and Soulin LIN***

*Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, People's Republic of China
**Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, People's Republic of China
***Department of Applied Chemistry, China University of Geosciences, Wuhan 430074, People's Republic of China

A direct sampling with organic solvent extracts for simultaneous multi-element determination implemented with inductively coupled plasma atomic emission spectrometry (ICP-AES) associated with a flow injection liquid-liquid extraction (FI-LLE) sample preconcentration method was studied. The “obustness” of the plasma discharge with tributyl phosphate (TBP) loading was diagnosed by using the Mg II 279.55 nm and Mg I 285.21 nm lines intensity ratio. A FILLE preconcentration system for rare earth elements (REEs)-nitrate-TBP was established by using a laboratory-designed phase separator. For these elements, an average sensitivity enhancement factor of 64 was obtained with respect to ICPAES sampling with aqueous solutions. The precision of the method was characterized by a relative standard deviation (%RSD) of 1.8 - 5.2%. A throughput of 27 samples per hour can be achieved with an organic solvent consumption of less than 200 μl per determination. Good results were obtained for the analysis of standard reference materials.

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