Analytical Chemistry Division, Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
Anal Chem. 2009 Mar 15;81(6):2208-17. doi: 10.1021/ac802251n.
High-performance inductively coupled plasma optical emission spectrometry (HP-ICP-OES) was used to certify the Be mass fraction in National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 1877 Beryllium Oxide Powder. The certified value and expanded uncertainty expressed at a 95% confidence level is (0.3576 +/- 0.0024) g/g. To obtain best results, the Be mass fractions, Mn (internal standard) mass fractions, and matrix compositions of the calibration solutions were carefully matched to those of the sample solutions for each individual HP-ICP-OES analysis. This "exact matching" approach was used because experience at NIST has shown that it often affords improved accuracy and precision in HP-ICP-OES analysis. NIST has never published these observations. Due to the toxicity of BeO and the difficulty of containing the very fine powder material, sets of solutions for HP-ICP-OES analysis were prepared by laboratories collaborating with NIST who have the experience and equipment needed to work with the material safely. Each laboratory utilized a unique digestion protocol(s). After preparing the sets of solutions, the collaborating laboratories shipped them to NIST for HP-ICP-OES analysis. NIST provided the collaborating laboratories with solution preparation kits and spreadsheets to help establish traceability of the HP-ICP-OES results to the International System of Units (SI) and to allow exact matching to be accomplished. The agreement observed among the four individual Be mass fraction values determined from the sets of solutions prepared by the collaborating laboratories was 0.074% relative (1s of mean). The excellent agreement provides a measure of confidence in the robustness of each of the digestion procedures, as well as in the certified Be mass fraction value. The analytical benefits of using exact matching for this particular certification were investigated. Results show that exactly matching the matrix compositions of the standards to the samples for each HP-ICP-OES analysis was critical to obtaining the excellent agreement observed among the individual Be mass fraction values and also helped to minimize bias and uncertainty in the certified value. Unlike previous NIST studies, exactly matching the Be and Mn mass fractions of the standards to the samples for this particular certification appears to have had little effect on the data.
采用高性能电感耦合等离子体发射光谱法 (HP-ICP-OES) 对美国国家标准与技术研究院 (NIST) 标准参考物质 (SRM) 1877 氧化铍粉末中的铍质量分数进行了认证。经认证的数值及其在 95%置信水平下的扩展不确定度为 (0.3576 +/- 0.0024) g/g。为了获得最佳结果，对于每个单独的 HP-ICP-OES 分析，校准溶液中的铍质量分数、Mn（内标）质量分数和基体组成都经过精心匹配，与样品溶液中的相应数值相匹配。之所以采用这种“精确匹配”方法，是因为 NIST 的经验表明，它通常可以提高 HP-ICP-OES 分析的准确性和精密度。NIST 从未公布过这些观察结果。由于氧化铍的毒性以及容纳非常细的粉末材料的难度，用于 HP-ICP-OES 分析的溶液套装由与 NIST 合作的实验室制备，这些实验室具有安全处理材料所需的经验和设备。每个实验室都采用了独特的消解方案。在制备溶液套装后，合作实验室将其寄送至 NIST 进行 HP-ICP-OES 分析。NIST 为合作实验室提供了溶液制备套件和电子表格，以帮助将 HP-ICP-OES 结果追溯到国际单位制 (SI)，并实现精确匹配。由合作实验室制备的溶液套装确定的四个单独的铍质量分数值之间的一致性为 0.074%（平均值的 1s）。这种极好的一致性为每个消解程序的稳健性以及认证的铍质量分数值提供了可信度。还研究了针对此特定认证采用精确匹配的分析优势。结果表明，对于每个 HP-ICP-OES 分析，将标准的基体组成精确匹配到样品至关重要，这有助于实现各个铍质量分数值之间的极好一致性，并有助于最小化认证值中的偏差和不确定性。与之前的 NIST 研究不同，对于此特定认证，将标准中的铍和 Mn 质量分数精确匹配到样品似乎对数据没有什么影响。
