同位素稀释火花源质谱法定值测定茶叶和茶树叶标样中九种微量元素

Determination of Nine Trace Elements in Tea Standard Reference Materials

本工作研究了采用同位素稀释火花源质谱法定值测定茶叶中Th、Pb等九种微量元素的分析方法。本方法具有灵敏度高、多元素同时测定能力强以及无需标样即可进行定量测定等特点。工作中对样品的灰化方法、谱线干扰及测量线对和最佳稀释条件的选择进行了研究。采用长寿命放射性同位素^(280)Th作为Th的稀释剂,大为提高了0.1ppm数量级Th含量的测量准确度。最后采用本方法为中科院生态环境研究中心研制的茶叶和茶树叶标样中九个微量元素提供了定值分析数据,本方法测定值与标样标准值相符情况良好,18个数据的平均差为5%。

An isotope dilution spark source mass spectrometric method (ID—SSMS) has been developed for the certification of nine trace elements (Th, Pb, La, Ce, Cu, Zn, Rb, Sr, Ba) in home tea and tea leaves reference materials. The method of ashing, spectral interferences and selection of the interference-free lines and the optimum spike addition have been studied. The radio isotope ^(230)Th is applied as spike of Th. The determined concentrations are in good agreement with the certified values and the accuracy has been improved by this procedure.