ICP-MS法测定云南野生茯苓中矿质元素含量

Determination of Mineral Elements of Wild Wolfiporia extensa Collected from Yunnan by ICP-MS

建立微波消解电感耦合等离体质谱(inductively coupled plasma-mass spectrometry,ICP-MS)法测定云南野生茯苓中Li、Mg、K、Ca、V、Cr、Mn、Fe、Cu、Zn、As、Rb、Sr、Cs、Pb 15种矿质元素的分析方法,研究云南野生茯苓中矿质元素的含量分布特征。使用ICP-MS法对采集自云南省28个地区野生茯苓样品中15种矿质元素进行定量分析,并采用SPSS进行主成分分析,相关性分析和聚类分析对测定结果进行评价。结果显示,元素线性回归方程的相关系数r均大于0.999 0,15种测定元素均在推荐值(真实值)范围内,其相对标准偏差均小于8%,表明该方法具有较好的准确度和精密度,适用于云南野生茯苓中矿质元素的测定。所测试野生茯苓中含有丰富的矿质元素,其中Ca(925.79μg/g)、K(370.42μg/g)、Mg(115.20μg/g)和Fe(115.80μg/g)的含量较高,有毒重金属As(0.04μg/g)和Pb(0.20μg/g)的含量均未超出GB 2672—2012《食品中污染物限量》及联合国粮农组织/世界卫生组织关于有毒重金属限量标准。主成分分析结果显示前4个主成分可以解释全部变量信息的77.55%,得出云南野生茯苓的特征元素为V、Fe、Li、As、Cs、Cr、Pb、Sr、Ca、Mn。聚类分析将所测元素分为3类,其中Fe、V、Li、Cs、As、Cr、Pb聚为一类,K、Rb、Zn、Mg、Cu、Mn聚为一类,Ca、Sr聚为一类,元素之间的相关性和聚类分析结果与主成分分析的结果一致。不同产地茯苓样品的聚类分析结果表明,样品中矿质元素均存在很大差异,这可能是野生茯苓样品中矿质元素含量受云南地形地貌,气候特征影响较大。

This study was undertaken to investigate the distribution characteristics of mineral elements in wild Wolfiporia extensa. Fifteen elements including Li, Mg, K, Ca, V, Cr, Mn, Fe, Cu, Zn, As, Rb, Sr, Cs, and Pb in the sclerotia of W. extensa collected from 28 regions of Yunnan province were determined by inductively coupled plasma-mass spectrometry（ICP-MS） after microwave digestion. The measurement data were analyzed by SPSS through principle component analysis（PCA）, correlation analysis, and cluster analysis（CA）. The results showed that the correlation coefficients（r） of the linear regression equations of the anayte elements were all above 0.999 0, the measured values of standard reference materials were in agreement with the certified values, and the relative standard deviations（RSDs） were all below 8%. Hence this method is suitable for the determination of mineral elements of wild W. extensa because of its good precision and accuracy. Our analysis results indicated that wild W. extensa collected from Yunnan contained many kinds of mineral elements. The concentration levels of Ca（925.79 μg/g）, K（370.42 μg/g）, Mg（115.20 μg/g）, and Fe（115.80 μg/g） were the highest, and the levels of toxic elements As and Pb were below the maximum safe limits stipulated in the Standard for Maximum Levels of Contaminants in Foods（GB 2762—2012） and the FAO/WHO standards. The results of PCA indicated that 4 principal components were chosen to examine the dataset which could explain 77.55% of the total variance. V, Fe, Li, As, Cs, Cr, Pb, Sr, Ca, and Mn were inferred to be the characteristic elements in wild W. extensa. The results of correlation analysis and CA were in agreement with PCA. All the tested elements could be grouped into three clusters： Fe, V, Li, Cs, As, and Cr as the first cluster; and Pb, K, Rb, Zn, Mg, and Cu as the second cluster; and Mn, Ca and Sr as the third cluster. The results of CA indicated that there were significant differences in the contents of mineral elements mainly because the mineral element contents of wild W. extensa were greatly influenced by the topography and climate characteristics of Yunnan province.