电感耦合等离子体质谱分析中金属元素的基体效应

电感耦合等离子体质谱是目前痕量元素分析领域最重要的方法,基体效应制约了该技术在复杂基体样品中的应用。文章梳理了金属元素基体效应的产生机理,包括电离抑制、空间电荷效应和协同作用等,其中,协同作用能更好地解释在不同条件下的基体干扰,受到越来越多研究者的认同。讨论了碱金属、碱土金属、铁、铜基体下痕量元素检测面临的基体干扰情况,高浓度的金属元素基体可能会导致采样锥堵塞,造成信号的不规律损失,使分析精度变差,也可能抑制部分待测元素的信号,导致测定结果偏低。总结了基体效应常用消除或校正方法,包括仪器硬件优化、仪器测试参数优化、校准方法优化及化学分离等。文章可为金属元素基体中痕量元素的准确测定提供参考借鉴。

Quantitative analysis of the nickel base alloy by laser-induced breakdown spectroscopy in high vacuum environment

Laser-induced breakdown spectroscopy (LIBS) is a promising in-situ diagnosis technology for the wall materials in tokamak devices. Currently, it has been applied to the Experimental Advanced Superconducting Tokamak (EAST) devices, which can in real time, in situ and online monitor the surface composition of wall materials. But there is a challenge to get precisely quantitative result of wall surface in high vacuum environment. The high vacuum environment of EAST device was simulated, and five kinds of samples (nickel base alloy) were ablated by nanosecond pulsed laser to generate plasma and obtain spectra. The temperature and density of plasma were calculated by multi-Boltzmann slope method and Stark width method respectively. The One Point Correction method (OPC) was used to carry out quantitative research comparing with the Calibration-Free LIBS (CF-LIBS) method. The results showed OPC method could significantly improve the quantitative accuracy of each element in the alloy. For matrix element of Ni, the relative error was less than 3.92%. The relative error of Mo with atomic percent of 3.11% decreased from 155.41% to 34.32%. The quantitative method provided a theoretical reference for on-line measurement of impurity deposition on wall surface with LIBS technology.