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    X射线荧光光谱法半定量和电感耦合等离子体质谱法全定量快速测定花草茶中多种元素

    Rapid Determination of Multi-Elements in Herb Tea by Semi-Quantitative XRFS and Quantitative ICP-MS

    • 摘要: 采用粉末压片制备花草茶样片,以X射线荧光光谱无标准样品半定量法对5种花草茶样品进行全元素扫描得出所含元素的种类及含量范围;采用微波消解5种花草茶样品,以电感耦合等离子体质谱法进行多种元素的全定量测定。X射线荧光光谱法(XRFS)可以检出5种花草茶样品中质量分数在1 μg·g-1以上的所有金属元素和非金属元素,5种花草茶样品中均测定出钾、磷、硫、镁、钙、氯、硅、铁、锌和锰等10种元素,质量分数最高的元素为钾。根据XRFS测定结果优化电感耦合等离子体质谱法(ICP-MS)仪器工作条件及样品前处理方法。多种元素的质量浓度在一定范围内与其对应的信号强度呈线性关系,方法的检出限(3s)为0.001 8~35.27 μg·kg-1。ICP-MS测定结果与XRFS测定结果一致,砷、铅、镉、铬等4种重金属元素均可被检出。采用XRFS和ICP-MS对柑橘叶国家标准物质(GBW 10020)进行分析,XRFS和ICP-MS的测定值均在认定值范围内,XRFS测定值的相对标准偏差(n=6)均小于5.0%,ICP-MS测定值的相对标准偏差(n=6)均小于3.0%。对XRFS和ICP-MS测定镁、钾、钙、锰、铁、锌等6种金属元素的结果进行对比分析,趋势线斜率为0.761 2~1.306,相关性系数为0.910 8~0.999 8,可比性较好。

       

      Abstract: Semi-quantitative XRFS without standard sample was used to screening all of the elements in samples of five kinds of herb tea to obtain the types and content ranges of the elements contained after using powder pressed method to prepare the sample slice of herb tea. After microwave digestion of herbal tea sample, ICP-MS was applied to quantitative determination of multi-elements. XRFS could detect those metal elements and nonmetal elements which mass fraction more than 1 μg·g-1 in five kinds of herb tea samples. 10 elements, i.e. K, P, S, Mg, Ca, Cl, Si, Fe, Zn and Mn in five kinds of herb tea samples were all detected. The element with the highest mass fraction was K. According to XRFS determination results, the sample pretreatment method and instrument working conditions of ICP-MS were optimized. Linear relationships between values of signal intensity and mass concentration of multi-elements were kept in definite ranges. Detection limits (3s) of the method ranged from 0.001 8 to 35.27 μg·kg-1. Determination results of ICP-MS were consistent with XRFS. 4 heavy metal elements, i.e. As, Pb, Cd and Cr could be detected. The national reference material of citrus leave (GBW 10020) was determined by XRFS and ICP-MS, and determination results of XRFS and ICP-MS were all within the range of the certified values with RSDs (n=6) of determination results of XRFS and ICP-MS were less than 5.0%, 3.0% respectively. Determination results of 6 elements, i.e. Mg, K, Ca, Mn, Fe and Zn by XRFS and ICP-MS were compared. Slopes of trend lines were in the range of 0.761 2-1.306, and correlation coefficients ranged from 0.910 8 to 0.999 8. The two methods were good in comparability.

       

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