Analytical Chemistry Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
Anal Chem. 2010 Sep 15;82(18):7675-83. doi: 10.1021/ac101471a.
Exact matching is investigated as a means of improving high-performance inductively coupled plasma optical emission spectrometry (HP-ICP-OES), a technique developed at the National Institute of Standards and Technology (NIST) to enable elemental determinations with relative expanded uncertainty of approximately 0.2% expressed at 95% confidence. "Exact matching" refers to the very careful matching of analyte mass fractions, internal standard mass fractions, and matrix compositions among the calibration and unknown sample solutions prepared for an analysis. Computer spreadsheet modeling results and laboratory data involving 16 pairs of analyte and internal standard wavelengths show that exact matching of analyte and internal standard mass fractions mitigates imprecision and bias that can be caused by even subtle nonlinearity in the ICP-OES instrument response. Laboratory experiments also demonstrate matrix effects caused by small variations in acid composition and by mass fractions of Na less than 4 mg kg(-1), emphasizing the need for exact matching of matrix compositions. HP-ICP-OES analyses performed at NIST with and without exact matching illustrate that exact matching enables relative expanded uncertainties to be halved to approximately 0.1%.
精确匹配被研究作为一种改进高性能电感耦合等离子体光学发射光谱法（HP-ICP-OES）的方法，该技术是由美国国家标准与技术研究院（NIST）开发的，用于在 95%置信度下实现相对扩展不确定度约为 0.2%的元素测定。“精确匹配”是指在为分析准备的校准和未知样品溶液中，仔细匹配分析物质量分数、内标质量分数和基质组成。涉及 16 对分析物和内标波长的计算机电子表格建模结果和实验室数据表明，分析物和内标质量分数的精确匹配可以减轻由于 ICP-OES 仪器响应中的微小非线性引起的不精确性和偏差。实验室实验还证明了由酸组成的微小变化和 Na 质量分数小于 4mgkg(-1)引起的基质效应，强调了精确匹配基质组成的必要性。NIST 进行的带有和不带有精确匹配的 HP-ICP-OES 分析表明，精确匹配可以将相对扩展不确定度减半至约 0.1%。
