改进的氧瓶燃烧法结合电感耦合等离子体质谱快速测定茶叶样品中的稀土元素含量

Fast Determination of Rare Earth Elements in Tea Samples by ICP-MS with Modified Oxygen Flask Combustion

建立了电感耦合等离子体质谱法快速测定茶叶中Y^Lu共15种稀土元素的新方法,样品处理基于改进的氧瓶燃烧法,以涂覆甘油的石英布代替滤纸作为引燃和燃烧载体,在500 m L容积燃烧瓶中实现了0.1 g样品量的有氧完全燃烧。系统优化了样品处理关键参数,以5 m L 4%HNO_3+1%HF(V/V)组合试剂超声提取燃烧残渣1 min,稀土元素回收率大于90%,样品总处理周期小于3 min。6次样品平行测定值的相对标准偏差(RSD)在2.7%~5.5%之间,方法检出限(3σ)在0.001~0.006 mg/kg之间。采用本方法对3种茶叶标准参考物质进行分析,测定结果和标准值吻合良好。

A new method for accurate determination of 15 rare earth elements including Y-Lu in tea samples by inductively coupled plasma-mass spectrometry（ ICP-MS） was proposed. Sample preparation was based on the modified oxygen flask combustion technique. By using quartz cloth coated with glycerol instead of filter paper as the ignition agent,a total amount of 0.1 g sample could be completely burned in a 500-m L flask. Key factors affecting the sample preparation effect were systematically investigated,and it was found that the extraction efficiencies of over 90% for all the analytes could be realized with 5 m L of 4% HNO3＋ 1% HF（ V/V） as the extractant for the combustion residue and the total extraction process could be finished in one minute under sonication,which resulted in a very fast sample preparation procedure that could be completed in less than 3 minutes. The relative standard deviations（ RSD） of six parallel determination values were between2.7% and 5.5%,and the detection limits ranged from 0. 001 mg / kg to 0. 006 mg / kg. Three tea standard reference materials were analyzed with the method and the detection results agreed well with the standard values. The method was successfully applied to three real samples analysis.