电感耦合等离子体质谱法测定牛初乳粉中痕量硒的干扰探讨

目的 分析样品基体给检测结果造成的增敏效应影响,建立一种能消除待测样品中基体的干扰,从而准确测定痕量硒的电感耦合等离子体质谱的检测方法。方法 样品经硝酸消解后, 采用标准加入法,标准溶液加入的体积不大于待测液体积2%的前提下,在氦气模式下以元素特定质量数定性,以待测元素质谱信号与内标元素质谱信号的强度比与待测元素的浓度成正比进行定量分析。结果 样品基底对硒有增敏效果采用标准加入法能很好消除样品基底干扰,检测5种标准物质的硒含量均在标示值范围内。工作曲线相关系数达到0.998,精密度试验的相对标准偏差为3.2%。结论 该方法相对外标法能更准确对痕量硒进行定量,适合测定基底复杂存在干扰的样品,对相同或相近的样品可以共用相同工作曲线测定硒含量。

Discussion on interference in determination of trace selenium in bovine colostrum powder by inductively coupled plasma mass spectrometry

Objective To discuss the matrix interference factors in determination of trace selenium in bovine colostrum powder by inductively coupled plasma mass spectrometry (ICP-MS). Methods After the sample was digested with nitric acid, the standard addition method was used, and under the premise that the volume of the standard solution was not more than 2% of the volume of the solution to be determined, the qualitative analysis was carried out according to the specific mass number of elements in the helium mode. The intensity ratio of the mass spectrum signal of the element to be determined was proportional to the concentration of the element to be determined. Results The sample substrate could enhance the sensitivity of selenium. The interference of sample substrate could be eliminated by standard addition method. The content of selenium in 5 kinds of reference materials was all within the marked value range. The correlation coefficient of the working curve was 0.998, and the relative standard deviation of precision test was 3.2%. Conclusion This method is more accurate than external standard method for the determination of trace selenium, which is suitable for the determination of samples with complex matrix and interference. For the same or similar base samples, the same working curve can be used to determine selenium content.