Mass resolution and mass accuracy: how much is enough?
Mass resolution and mass accuracy: how much is enough?
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DOI：
10.5702/massspectrometry.s0009
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发表时间：
2013-01-01
期刊：
影响因子：
--
通讯作者：
Xian, Feng
中科院分区：
文献类型：
--
作者：
G Marshall, Alan;T Blakney, Greg;Xian, Feng
精确的质量测量需要尽可能高的质量分辨率，以确保只有单一元素成分对所讨论的质谱峰有贡献。尽管质量分辨率通常定义为两个等高和宽的峰之间最接近的可区分间隔，但对于峰高比为 100:1 的等宽峰，所需的质量分辨率可能高出 10 倍。因此，最小分辨率需要最大动态范围的规格，因此比传统清晰度高 10-100*。质量分辨能力还取决于质荷比。质量精度取决于质谱信噪比和数字分辨率。最后，通过同位素精细结构的解析可以提高元素成分分配的可靠性。因此，要回答“多少才算足够的质量分辨能力”这一问题，需要首先指定信噪比、动态范围、数字分辨率、质荷比和（如果有的话）同位素精细结构。最高的可用宽带质量分辨率和质量精度来自傅里叶变换离子回旋共振质谱。在过去五年中，基于更高的磁场强度、时域瞬变的条件平均、更好的质量校准（光谱分割；包含空间电荷项），FT-ICR MS 质量精度提高了大约一个数量级；径向分散激励；相位校正以产生吸收模式显示；以及新的 ICR 细胞分割设计。
Accurate mass measurement requires the highest possible mass resolution, to ensure that only a single elemental composition contributes to the mass spectral peak in question. Although mass resolution is conventionally defined as the closest distinguishable separation between two peaks of equal height and width, the required mass resolving power can be 10* higher for equal width peaks whose peak height ratio is 100:1. Ergo, minimum resolving power requires specification of maximum dynamic range, and is thus 10-100* higher than the conventional definition. Mass resolving power also depends on mass-to-charge ratio. Mass accuracy depends on mass spectral signal-to-noise ratio and digital resolution. Finally, the reliability of elemental composition assignment can be improved by resolution of isotopic fine structure. Thus, the answer to the question of "how much is enough mass resolving power" requires that one first specify S/N ratio, dynamic range, digital resolution, mass-to-charge ratio, and (if available) isotopic fine structure. The highest available broadband mass resolving power and mass accuracy is from Fourier transform ion cyclotron resonance mass spectrometry. Over the past five years, FT-ICR MS mass accuracy has improved by about an order of magnitude, based on higher magnetic field strength, conditional averaging of time-domain transients, better mass calibration (spectral segmentation; inclusion of a space charge term); radially dispersed excitation; phase correction to yield absorption-mode display; and new ICR cell segmentation designs.