利用AutoPrep离子色谱技术实现复杂基体样品中重稀土元素的分离和制备

Separation and Preparation of Heavy Rare Earth Elements in Samples with Complex Matrix by AutoPrep Ion Chromatography

研究了AutoPrep自动前处理装置和离子色谱联用技术分析复杂基体样品中重稀土元素的分离和半制备的方法。选用两个双层四通阀和一个六通阀替代传统方法中的四个双层四通阀,选用一个GS50四元梯度泵实现对螯合浓缩柱不同条件的淋洗,将吸附或交换在螯合柱和浓缩柱上的碱金属、碱土金属、过渡金属、重金属和重稀土元素选择性地分段洗脱,并将基体消除后的样品在线进样到CS5A离子色谱交换柱中进行最终分离,过柱衍生后进入紫外-可见光检测器进行光度检测,并根据确定的保留时间段进行在线样品收集,完成制备工作。对基体简单且被测组分含量较高的样品,采用直接进样法测定4种重稀土元素(Tb、Y、Tm和Lu)的检测限(S/N=3)为8.3-21.0μg/L,线性相关系数均大于0.9992,分离度均大于4,以峰面积计算的方法精密度(RSD,n=9)小于3%,回收率为89.0%-110.8%;对复杂基体样品或被测组分含量较低的样品,采用基体消除在线浓缩处理,方法的检测限(S/N=3)为0.67-1.43μg/L,线性相关系数均大于0.9994,分离度均大于3,方法的精密度(RSD,n=9)小于3%,回收率为91.2%-106.0%。对简单基体和复杂基体两种样品的分离和制备方法均具备灵敏度高、选择性好、自动化程度高、节省时间等特点,用于岩石等实际样品的检测,结果满意。

This paper introduces a method for separating and collecting heave rare earth elements in samples with complex matrix by AutoPrep pretreatment device combined with ion chromatographic technique. Two 8-port valves were selected in this method instead of eight 4-port valves used in traditional method, while a GS50 4-channel gradient pump was employed to provide different elution conditions in order to selectively eluting anions, alkali metals, alkaline-earth metals, transition metals and heavy rare earth elements step by step. Then the matrixeliminated samples were injected to CS5A double selective column bv switching the 6- port valve to inject position to obtain the final separation of residue metals. The analytes were then determined by UV-VIS detector with wavelength of 520 nm after post column derivation reaction. The element collection was implemented by on-line collecting solutions from the cell-out tube during particular time fractions confirmed by the former chromatograms when the flow of post column device was turned off. For the samples with simple matrix and high concentration of analytes, direct injection method was used with detection limits of 8.3 -21.0μL （S/N = 3 ） and linearity relative coefficients of higher than 0.9992. The resolution between each two peaks was higher than 4 and the precision of the method for peak areas was less than 3% RSD （n =9） with spiked recovery of 89.0% - 110.8%. For the sampies with complex matrix or low concentration of analytes, preconcentration and matrix elimination method was used. In this case, the detection limits of 0.67 - 1.43 μg/L （ S/N= 3 ） and linearity relative coefficients of higher than 0.9994 were obtained. The resolution between any two peaks was higher than 3 and the precision of the method for peak areas was less than 4% RSD （n =9） with spiked recovery of 91.2% -106.0%. Both methods possess of the advantages of high sensitivity, good selectivity, high automatization and time-saving. The results for actual rock sample analysis are satisfactory.