An analysis method was established for the determination of Se ( FV ) and Se ( VT) in soil samples by Hydride Generation-Atomic Fluorescence Spectrometry ( HG-AFS) , the key point being the selection of the extraction agent. In the past, there were so many kinds of extraction agents, but no pertinence. The extraction capacity of different extraction agents was compared and KH2PO4-K2HPO4 solution was selected for the experiment, which has a pH value of 8. 5. The total content of Se was measured by using 6 mol/L HC1 as reducing agent and being heated in a boiling water bath for 30 min. The content of Se ( IV ) was measured by the solution without heating in the boiling water bath. Finally, the content of Se( VI) was yielded by total Se content subtracted from the Se (IV). In the acidity condition of this experiment, the interference of coexisting elements was eliminated by adding Fe( HI ) salt. The relative standard deviation was 5. 0% - 12. 6% (re = 11) , linear range was 0. 00 -6. 00 |xg/L, the recovery was 90. 0% - 112. 5% and the detection limit was 0. 347 u,g/L. The method has been applied to determinate trace Se in reference materials and the results were in agreement with certified values. The results indicate that the method is simple, quick and highly sensitive. It is a feasible method to detect different valence states of Se in soil samples.%采用氢化物发生-原子荧光光谱法( HG - AFS)测定土壤样品中Se(Ⅳ)和Se(Ⅵ)时,提取剂的选择是技术的关键.以往的提取剂种类多且不具有针对性,本文对比了不同提取剂的提取能力,确定使用KH2PO4 - K2HPO4溶液(pH=8.5)为实验用提取剂,以6 mol/L HCl作为还原剂,沸水浴30 min后HG - AFS测定Se总量,不加热直接测定Se(Ⅳ)含量,以差减法得出Se(Ⅵ)含量.在本实验酸度条件下,加入三价铁盐,可消除共存元素的干扰.方法回收率为90.0％ ～ 112.5％,线性范围为0.00 ～6.00 μg/L,相对标准偏差为5.0％ ～ 12.6％ (n=11),方法检出限可达到0.347 μg/L.标准物质的测定值与标准值相符.实验证实此方法提取效果好,是测定土壤样品中硒不同价态的可行性方法.
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