优化Rpa电压-电感耦合等离子体质谱法测定铁皮石斛中不同部位的14种金属元素

Determination of 14 Elements in Different Parts of Dendrobium Officinale by Inductively Coupled Plasma Mass Spectrometry with Optimization of Rpa Voltage

建立了优化Rpa电压-电感耦合等离子体质谱法测定铁皮石斛中不同部位的Mg、Al、K、Ca、Cr、Mn、Fe、Cu、Zn、Ni、As、Se、Cd和Pb 14种金属元素的方法。样品经微波消解后,采用动态反应池去除样品基体带来的质谱干扰,同时针对部分高含量元素的信号溢出问题,实验优化了Rpa电压,免去了样品的二次稀释。各元素的检出限为0.02-32μg/L,日内精密度（RSD,n=6）和日间精密度（RSD,n=12）分别在0.7%-4.6%和1.5%-5.8%之间;样品的加标回收率为83.9%-112%。采用该方法对柑橘叶标准样品（GBW10020）进行了验证,测定值均在参考值范围内。方法对大棚种植的铁皮石斛的不同部位样品进行了测定,发现重金属含量处于较低水平,其中叶和花的重金属含量要显著高于茎中的含量。

An inductively coupled plasma mass spectrometry（ICP-MS）with dynamic reaction cell method was developed for the determination of Mg,Al,K,Ca,Cr,Mn,Fe,Cu,Zn,Ni,As,Se,Cd,Pb and Al in different parts of dendrobium officinale.After microwave digestion,the sample solution was introduced to the ICP-MS system.Dynamic reaction cell with ammonia as the reaction gas was optimized to minimize spectral interferences.Rpa value was also optimized to depress the signal response of high concentration level elements to avoid further diluting.The detection limits for measured elements were from 0.02 to 32μg/L,respectively.The relative standard deviations（RSD）of within-day and between-days were from0.7%to 4.6% and 1.5to 5.8%,respectively.The recoveries of the optimized method were in the range of 83.9%-112% with RSDs6%.The concentrations of the certified reference material of citrus（GBW10020）determined by this method were in compliance with the reference values,indicating the validation and applicability of the method.The optimized method was applied to the determination of metallic elements in different parts of dendrobium officinale.It was observed that the concentration of heavy metal（As,Cu,Cd and Pb）in different parts were at low levels,and the concentration of heavy metal in leaf and flower were higher than those in stem.