Comparison and interconversion of the two most common frequency-to-mass calibration functions for Fourier transform ion cyclotron resonance mass spectrometry
Comparison and interconversion of the two most common frequency-to-mass calibration functions for Fourier transform ion cyclotron resonance mass spectrometry
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DOI：
10.1016/s1387-3806(99)00226-2
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发表时间：
2000-01-21
影响因子：
1.8
通讯作者：
Marshall, AG
中科院分区：
文献类型：
--
作者：
Shi, SDH;Drader, JJ;Marshall, AG
在一个完美的三维轴向四极静电势场,Ledford等人表明,m / z = frequency-to-mass标定关系(左)/ v + bl / v(2)有效期为离子的质荷比,m / z < (m / z)(关键)= e B (0) (2) (2) / 4 v(陷阱)α,v是“减少”(观察)离子回旋频率,e是电子(小学),z是基本费用/离子的数量,B 0,是磁场感应,是一种特征维度,v（陷阱）是应用于每个陷阱末端的电位，alpha是由陷阱几何结构决定的常数，a (L)和B-L是通过拟合傅里叶变换ICR （FT-ICR）质谱中至少两个已知质量的离子的实验离子回旋共振（ICR）频率来确定的常数。在m/z远小于（m/z）（临界）的进一步限制下，Francl等人得到了不同的频率-质量关系m/z = a (F)/(B-F + v)。在这里，我们重新推导频率-质量关系，以推导a (L)和B-L与a (F)和B-F之间的简单转换（例如，用于比较来自不同供应商的校准FT-ICR质谱数据）。对于精确的质量测量，转换会引入一个通常可以忽略的小误差（十亿分之几）。更重要的是，通过将两个校准方程应用于相同的实验时域数据，我们发现两个校准函数（或它们的相互转换）产生的质量精度是无法区分的，因为Ledford等人的效度标准m/z < 0.001 (m/z)（临界）通常满足具有优化单元几何形状的现代高场仪器。有趣的是，当使用不同形式的相同校准函数时，可能会产生较小的差异，这可能是由于计算中的舍入误差不同。(C) 2000爱思唯尔科学有限公司
In a perfect three-dimensional axial quadrupolar electrostatic potential field, Ledford et al. showed that the frequency-to-mass calibration relation m/z = A(L)/v + B-L/v(2) is valid for ions of any mass-to-charge ratio, m/z < (m/z)(critical) = e B(0)(2)a(2)/4V(trap)alpha, in which v is the "reduced" (observed) ion cyclotron frequency, e is the electronic (elementary) charge, z is the number of elementary charges per ion, B-0, is magnetic field induction, a is a characteristic trap dimension, v(trap) is the potential applied to each trap endcap, alpha is a constant determined by the trap geometrical configuration, and A(L) and B-L are constants that are determined by fitting experimental ion cyclotron resonance (ICR) frequencies for ions of at least two known masses in a Fourier transform ICR (FT-ICR) mass spectrum. In the further limit that m/z much less than (m/z)(critical), Francl et al. obtained a different frequency-to-mass relation m/z = A(F)/(B-F + v). Here, we rederive both frequency-to-mass relations to derive a simple conversion between A(L) and B-L, versus A(F) and B-F (e.g, for comparing calibrated FT-ICR mass spectral data from different vendors). For accurate mass measurement, the conversion introduces a small error (a few parts per billion) that can usually be neglected. More important, by applying both calibration equations to the same experimental time-domain data, we find that mass accuracy resulting from the two calibration functions (or their interconversion) is indistinguishable, because Ledford et al,'s validity criterion, m/z < 0.001 (m/z)(critical), is generally satisfied for modern high-field instruments with optimized cell geometry. Interestingly, a small difference may result when different forms of the same calibration function are employed, presumably due to different roundoff errors in the calculation. (C) 2000 Elsevier Science B.V.