激光剥蚀电感耦合等离子体质谱无内标定量分析钢铁样品

在探讨内标法和基体归一法校准的基本原理基础上,建立了193 nm ArF准分子激光剥蚀电感耦合等离子体质谱无内标定量分析钢铁标样的方法。结果表明,采用Fe作内标和基体归一法(无内标)两种校正方法获得的中低合金钢GBW01398、含氮铸铁GBW01138和不锈钢GBW01659分析结果相对误差在5%以内。与传统的内标法相比,采用基体归一校准法的最大优点是无需预先知道样品中某一内标元素的含量即可进行定量。这一特点使得该技术也可适用于难以找到均匀分布的内标元素的样品的空间分布测定。剥蚀坑电镜扫描图像显示的波浪形底以及剥蚀坑周围显著拓展的外缘表明样品在剥蚀过程中,由于"热效应"发生了较严重的部分熔融。计算的分馏因子表明钢铁标样中元素V、Cr、Fe、Co、Ni和Cu的分馏因子与所用的外标参考物质NIST 610相似,接近于1且标准偏差较小。其它大部分微量元素由于含量低和分布不均一造成计算得到的元素分馏因子标准偏差特别大。钢铁标样中Cr、Fe、Co、Ni测定值与认定值的相对偏差都在10%以内。本文还发现Mg和轻稀土以及Bi和Pb在钢铁标样GBW01138中的分布具有很好的相关性。

Quantitative analysis of steel by laser ablation-inductively coupled plasma mass spectrometry without applying an internal standard

A quantitative analysis method of standard steel samples by 193 nm ArF excimer laser ablation inductively coupled plasma mass spectrometry without applying an internal standard has been reported. The relative error of results obtained by using conventional internal standard calibration method or our proposed matrix normalization method (internal standard-independent) is within 5% for low-alloy steel GBW01398, nitrogen-containing cast iron GBW01138 and stainless steel GBW01659. A clear advantage of the proposed method is free of the internal standard, which makes it suitable for spatially resolved analysis in minerals in which internal standard elements are difficult to find because of their heterogeneous distribution. The image of scan electron microscope of the ablation crater shows a wave-shaped bottom as well as a significant expansion around the edge of the sample crater, which indicates a serious partial melting occurred during the process of laser ablation due to " heat effect". Six elements (V, Cr, Fe, Co, Ni and Cu) in steel samples have similiar fractionation factor value with external standard reference material NIST 610 whose values are close to 1 with small standard deviation. However, the standard deviation of fractionation factors of other micro elements are considerably large, which is attributed to their heterogeneous distribution and low content. Most of the determined values of Cr, Fe, Co, Ni in steel reference materials agree within 10% with the reported certified values. There are excellent positive correlations between Mg and light rare earth elements as well as between Bi and Pb in steel sample GBW01138.