Electrically Compensated Fourier Transform Ion Cyclotron Resonance Cell for Complex Mixture Mass Analysis
Electrically Compensated Fourier Transform Ion Cyclotron Resonance Cell for Complex Mixture Mass Analysis
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DOI：
10.1021/ac201546d
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发表时间：
2011-09-01
影响因子：
7.4
通讯作者：
Marshall, Alan G.
中科院分区：
文献类型：
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作者：
Kaiser, Nathan K.;Savory, Joshua J.;Marshall, Alan G.
复杂的天然有机混合物，如石油，需要超高的质谱分辨率来分离和识别数千种元素组成。在这里，我们结合了一个定制的，电压补偿的ICR电池，用于傅立叶变换离子回旋共振质谱（FTICR MS），基于Tolmachev的先前设计，以产生最佳的质量分辨率。安装在定制的9.4 T FTICR质谱仪中的补偿ICR电池由7个轴向比例的圆柱形部分组成，旨在产生接近理想的三维轴向四极电位的直流捕获电位。然而，经验优化的补偿电压并不符合大多数四极俘获场。补偿电极通过平衡磁场和电场中的缺陷来最小化减少的回旋加速器频率的变化。施加在补偿电极上的优化电压使离子云相干性保持了大约2倍的更长的瞬态持续时间，从而能够分离和识别石油中常见的等压物质（具有相同标称质量但不同精确质量的化合物），例如C-3 VS SH4（由3.4 mDa分离）和(SH3C)-C-13 VS C-12(4)（由1.1 mDa分离）。改进后的ICR电池提供了更对称的峰形和更好的质量测量精度。正离子大气压光电离（APPI）石油光谱产生超过26000个指定峰，在m/z 500 （6.6 s瞬态持续时间）的傅里叶限制分辨率为80万，均方根误差为124亿分之一。补偿电极的可调性是获得最佳性能的关键。
Complex natural organic mixtures such as petroleum require ultrahigh mass spectral resolution to separate and identify thousands of elemental compositions. Here, we incorporate a custom-built, voltage-compensated ICR cell for Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS), based on a prior design by Tolmachev to produce optimal mass resolution. The compensated ICR cell installed in a custom-built 9.4 T FTICR mass spectrometer consists of seven cylindrical segments with axial proportions designed to generate a dc trapping potential that approaches an ideal three-dimensional axial quadrupolar potential. However, the empirically optimized compensation voltages do not correspond to the most quadrupolar trapping field. The compensation electrodes minimize variation in the reduced cyclotron frequency by balancing imperfections in the magnetic and electric field. The optimized voltages applied to compensation electrodes preserve ion cloud coherence for longer transient duration by approximately a factor of 2, enabling separation and identification of isobaric species (compounds with the same nominal mass but different exact mass) common in petroleum, such as C-3 VS SH4 (separated by 3.4 mDa) and (SH3C)-C-13 vs C-12(4) (separated by 1.1 mDa). The improved performance of the ICR cell provides more symmetric peak shape and better mass measurement accuracy. A positive ion atmospheric pressure photoionization (APPI) petroleum spectrum yields more than 26 000 assigned peaks, Fourier-limited resolving power of 800 000 at m/z 500 (6.6 s transient duration), and 124 part per billion root mean square (rms) error. The tunability of the compensation electrodes is critical for optimal performance.