On-Line Preconcentration of Rare-Earth Elements in Astragalus Membranaceus with Ion-Exchange Micro-Column and Their Determination by Inductively Coupled Plasma Atomic Emission Spectrometry

An analytical circuit,including a FIA manifold for separation and preconcentration of rare-earth (RE) elements from the Chinese medicine astragalus membranaceus with ion-exchange micro-column and the detection unit of ICP-AES,was designed and proposed.The ion-exchange resin 005×7 was chosen for the separation,and filled in a micro-column,which was installed in the FIA flow system.As shown by the experimental results,16 RE elements were effectively separated from the sample matrix and enriched by passing the sample solution (pH 1.0) through the micro-column at a flow-rate of 4 mL·min-1,and the RE elements were eluted from the column quantitatively and rapidly with 4 mol·L-1 HCl,and an enrichment multiple of 32 to 42 was obtained.The eluate was used directly for ICP-AES determination.The proposed method has been applied to the determination of 16 RE elements in a sample of astragalus membranaceus from Inner Mongolia,and RSD′s (n=6) of the results obtained were in the range of 1.2%-4.7%.The detection limits (3S) found were in the range of 0.09-2.49 μg·L-1.Results of recovery test were found in the range of 91%-110%.In the analysis of a SRM of tea leaves (GBW 07605) for its RE contents by this method,the results obtained were in consistency with the certified values.