Study on carbon-induced signal enhancement in inductively coupled plasma mass spectrometry: an approach from the spatial distribution of analyte signal intensities
Study on carbon-induced signal enhancement in inductively coupled plasma mass spectrometry: an approach from the spatial distribution of analyte signal intensities
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DOI：
10.1039/c9ja00152b
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发表时间：
2019-09-01
影响因子：
3.4
通讯作者：
Inagaki, Kazumi
中科院分区：
文献类型：
--
作者：
Ariga, Tomoko;Zhu, Yanbei;Inagaki, Kazumi
为了进一步了解碳诱导信号增强的机制，研究了电感耦合等离子体质谱（ICP-MS）中碳诱导信号增强的精确定量。通过测量含碳和不含碳的元素溶液（即5% (v/v) 2-丙醇，IPA），得到ICP中分析物离子（M+）的空间强度分布和轴向强度分布。5% (v/v) IPA的加入显著地扩展和移动了M+强度区，特别是在轴向，向采样锥方向。结果表明，为了准确定量，应考虑碳诱导的轴向区移。作为量化碳诱导信号增强的指标，根据轴向强度分布定义了一个增强因子（EFsum），即用5% (v/v) IPA获得的4 ~ 15 mm轴向采样位置的分析物信号强度之和除以没有5% (v/v) IPA获得的分析物信号强度之和。估计了26种元素的EFsum值，这些元素的第一电离能（IEs）和分析物氧化键离解能（BDEs）范围很广。EFsum值与元素的IEs或BDE之间没有明确的关系，尽管现有关于碳诱导信号增强机制的假设表明IE或BDE是决定碳诱导信号增强的主要因素。估计P、As、Se和i的EFsum值较大。这些元素在单质溶液中的化学形式通常是氧化酸。这一结果可能暗示了一种依赖于元素化学形态的机制也参与了碳诱导的信号增强。
To obtain further insight into the mechanism of carbon-induced signal enhancement, accurate quantification of carbon-induced signal enhancement in inductively coupled plasma mass spectrometry (ICP-MS) has been examined. Spatial intensity distributions and axial intensity profiles of the analyte ion (M+) in ICP were obtained by measuring elemental solutions with and without carbon (i.e., 5% (v/v) 2-propanol, IPA). Addition of 5% (v/v) IPA significantly spread and shifted the M+ intensity zone, particularly in the axial direction, toward the sampling cone. The result indicated that the carbon-induced zone-shift in the axial direction should be considered for accurate quantification. As an index for quantifying carbon-induced signal enhancement, an enhancement factor (EFsum), was defined based on the axial intensity profiles by dividing the sum of analyte signal intensities for axial sampling positions from 4 to 15 mm, obtained with 5% (v/v) IPA, by the sum of those obtained without 5% (v/v) IPA. The EFsum values were estimated for 26 elements with a wide range of first ionization energies (IEs) and analyte oxide bond dissociation energies (BDEs). There was no clear relationship between EFsum values and IEs or BDEs of elements, even though the existing hypotheses about the mechanism of carbon-induced signal enhancement have suggested that IE or BDE was a major factor that determines carbon-induced signal enhancement. Large EFsum values were estimated for P, As, Se, and I. Chemical forms of these elements in elemental solutions are oxoacids in common. The results might imply that a mechanism that depends on the chemical forms of elements is also involved in carbon-induced signal enhancement.