密闭消解-电感耦合等离子体质谱法测定小麦样品中的Cr、Ni、Cd、As

Determination of Cr, Ni, Cd, As in Wheat Samples by the Method of Airtight Digestion and Inductively Coupled Plasma Mass Spectrometry

选用5mL HNO3在140℃时对小麦样品进行密闭消解,并置于电热板上将NO2气体赶尽,定容至25mL后,以In、Ge、Rh、Re为内标溶液,建立了电感耦合等离子体质谱仪测定小麦样品中Cr、Ni、Cd、As四种重金属污染元素的方法。通过对质谱干扰、试剂空白、消解温度及消解时间等方面进行深入探讨,确定了最佳试验方案。本方法具有空白值低、消解完全、污染小、效率高、可操作性强等优势,方法检出限为0.001~0.085μg/g,Cr、Ni、Cd、As的线性相关系数均大于等于0.9999,采用实验方法对小麦粉成分分析标准物质NCS101017、NCS101018进行分析,相对标准偏差(RSD,n=12)为5.59%~14.44%,相对误差(RE,n=12)为-6.60%~9.96%。

A method for the determination of Cr, Ni, Cd and As in wheat samples by inductively coupled plasma mass spectrometry(ICP-MS) with In, Ge, Rh and Re as mixed internal standard solution was established. At first, airtight digestion of wheat samples was carried out with 5 mL HNO3 at 140 °C, and then the nitric oxide gas was removed from wheat samples with electric heating plate. At last, after constant volume to 25 mL, the contents of Cr, Ni, Cd and As in wheat samples were determined by ICP-MS with In, Ge, Rh and Re as internal standard solutions. The best test scheme was determined through in-depth discussion on mass spectrometry interference, reagent blank, digestion temperature and digestion time. The method had the advantages of low blank value, complete digestion, little pollution,high efficiency, and strong operability. The detection limit of the method was 0.001~0.085 μ g/g, and the linear correlation coefficients of Cr, Ni, Cd and As were all greater than or equal to 0.999 9. The method was used to analyze the standard substances NCS101017 and NCS101018 for the analysis of wheat flour. The relative standard deviation(RSD, n= 12) was 5.59 %~14.44 %, and the relative error(RE, n = 12) was-6.60 %~9.96 %.