Jones Willis B, Crossman Abigail J, Jones Bradley T
Department of Chemistry and Biochemistry, University of North Florida, Jacksonville, Florida 32224, United States.
Department of Chemistry, Wake Forest University, Winston-Salem, North Carolina 27109, United States.
Anal Chem. 2024 Jul 23;96(29):11906-11914. doi: 10.1021/acs.analchem.4c01614. Epub 2024 Jul 9.
Calibration by Proxy (CbPx) is a matrix-matched calibration method that utilizes multiple internal standard species to build a calibration curve. The technique requires only two solutions: solution 1 containing a sample solution and a suite of internal standards at known concentrations, and solution 2 identical to solution 1, plus an aliquot of a standard containing all analytes and the internal standards at the same concentration. The calibration curve is prepared by plotting the signal measured for each internal standard in solution 1 divided by the signal arising due to the aliquot of internal standard added to solution 2 on the -axis. In this ratio, the sensitivity for each element cancels, because the sample matrix is equal between the solutions. Therefore, the -axis value measured for a specific internal standard is identical to the value that would be measured for any other element present at the same concentrations in the two solutions. Hence, each internal standard serves as a proxy for analyte values. The concentrations of internal standards in solution 1 are plotted on the -axis, and these correspond to any analytes present in solution 1 at the same concentration. CbPx is applied to the analysis of five certified reference materials by inductively coupled plasma optical emission spectrometry (ICP-OES). Percent recoveries for analytes range from 89 to 106%, with relative standard deviations on the order of 1%. A recommended working range for the method is developed through both theoretical simulation and experimental results and then exhibited through the analysis of off-the-shelf vitamin tablets.
代理校准（CbPx）是一种矩阵匹配校准方法，它利用多种内标物来构建校准曲线。该技术仅需要两种溶液：溶液1包含样品溶液和一系列已知浓度的内标物，溶液2与溶液1相同，再加上一份含有所有分析物和相同浓度内标物的标准溶液的等分试样。校准曲线是通过将溶液1中每种内标物测得的信号除以由于添加到溶液2中的内标物等分试样而产生的信号，并绘制在x轴上而制备的。在此比率中，每种元素的灵敏度相互抵消，因为两种溶液中的样品基质相同。因此，针对特定内标物测得的x轴值与在两种溶液中以相同浓度存在的任何其他元素测得的值相同。因此，每种内标物都可作为分析物值的替代物。将溶液1中内标物的浓度绘制在x轴上，这些浓度对应于溶液1中以相同浓度存在的任何分析物。通过电感耦合等离子体发射光谱法（ICP-OES）将CbPx应用于五种有证标准物质（CRM）的分析。分析物的回收率在89%至106%之间，相对标准偏差约为1%。通过理论模拟和实验结果确定了该方法的推荐工作范围，然后通过对市售维生素片的分析展示了该范围。
