Optimum waveforms for differential ion mobility spectrometry (FAIMS)
Optimum waveforms for differential ion mobility spectrometry (FAIMS)
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DOI：
10.1016/j.jasms.2008.05.008
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发表时间：
2008-09-01
影响因子：
3.2
通讯作者：
Smith, Richard D.
中科院分区：
文献类型：
--
作者：
Shvartsburg, Alexandre A.;Smith, Richard D.
差分迁移谱或场非对称波形离子迁移谱 (FAIMS) 是一种分离和识别气相离子的新工具，特别是与质谱结合使用效果不佳。在 FAIMS 中，使用不对称波形，通过高电场强度 (L) 和低电场强度 (L) 下气体迁移率 (K) 之间的差异来过滤离子。无数可能的波形轮廓使得在工程限制内最大化性能成为 FAIMS 技术改进的主要问题。早期的优化假设迁移率的非恒定分量按比例缩放为 E-2，对所有离子产生相同的结果。在这里，我们表明，最佳轮廓是由 K(E) 的全级数展开定义的，其中包括与 L 成比例的第一项之外的项。对于许多离子/气体对，前两项具有不同的符号，并且 FAIMS 中 L 足够高时的最佳轮廓可能与之前报告的那些有很大不同，从而将 LIP 的分辨率提高到 2.2 倍。所有 FAIMS 系统中的某些离子都会出现这种情况，但在最近采用更高 E 的小型化设备中变得更加常见。根据实际的 K(E) 依赖性，最大波形幅度不一定是最佳的，并且在某些情况下将其通过 Lip 减少到大约 20%、30% 是有益的。目前的发现与目标分析特别相关，其中分离取决于特定离子的 K(M) 函数之间的差异。
Differential mobility spectrometry or field asymmetric waveform ion mobility spectrometry (FAIMS) is a new tool for separation and identification of gas-phase ions, particularly ill conjunction with mass spectrometry. Ill FAIMS, ions are filtered by the difference between mobilities ill gases (K) at high and low electric field intensity (L) Using asymmetric waveforms. An infinite number of possible waveform profiles make maximizing the performance within engineering constraints a major issue for FAIMS technology refinement. Earlier optimizations assumed the non-constant component of mobility to scale as E-2, producing the same result for all ions. Here we show that the optimum profiles are defined by the full series expansion of K(E) that includes terms beyond the first that is proportional to L. For many ion/gas pairs, the first two terms have different signs, and the optimum profiles at sufficiently high L in FAIMS may differ substantially from those previously reported, improving the resolving power by LIP to 2.2 times. This situation arises for some ions in all FAIMS systems, but becomes more common ill recent miniaturized devices that employ higher E. With realistic K(E) dependences, the maximum waveform amplitude is not necessarily optimum, and reducing it by Lip to similar to 20%, to 30% is beneficial in some cases. The present findings are particularly relevant to targeted analyses where separation depends oil the difference between K(M) functions for specific ions.