Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA.
Anal Chem. 2009 Mar 1;81(5):1833-40. doi: 10.1021/ac802213p.
A waveform isolation method is described for the mass-selective transmission of ions through quadrupole mass filters, and it is implemented on a new tandem mass analyzer instrument. The method features the application of broad-band waveforms comprising appropriate frequencies to cause mass-selective instability in ions of particular mass-to-charge (m/z) and to transmit all others. The experiment is implemented in a tandem quadrupole system in which the first mass filter is a rectilinear ion trap (RIT) operated in a continuous mass-selective mode to transmit ions of ions of one or more arbitrarily selected m/z value(s). The second analyzer was used to verify the quality of the mass selection achieved using the first analyzer via conventional quadrupole ion trap mass-selective instability scanning. A new subtype of product ion tandem mass spectrometry (MS/MS) scan, termed the summed product ion scan, is demonstrated with a mixture of biological compounds. It is used to characterize product ions arising after simultaneous isolation and collisional activation of multiple precursor species, in this case ions of the same analyte generated in different charge states. The summed product ion scan can be useful for enhancing sensitivity for the analyte of interest or for providing more comprehensive information about an analyte than is available by monitoring a single ionized form of the analyte. The analytical performance of the waveform isolation method is tested using simple drug mixtures, and its potential for increasing overall yields in preparative mass spectrometry is explored briefly. It is shown that efficiencies of ca. 70% of ion transfer to a surface for ion soft landing surface can be achieved. The upper mass range is limited by axial acceleration arising from the stretched geometry, and one solution to this problem is provided.
一种波形隔离方法，用于通过四极杆质量过滤器对离子进行质量选择性传输，并在新型串联质谱分析仪仪器上实现。该方法的特点是应用适当频率的宽带波形，以使特定质荷比（m/z）的离子产生质量选择性不稳定性，并传输所有其他离子。该实验在串联四极杆系统中进行，其中第一质量过滤器是直线离子阱（RIT），以连续质量选择模式操作，以传输一个或多个任意选择的 m/z 值的离子。第二个分析仪用于通过传统的四极杆离子阱质量选择性不稳定性扫描验证使用第一个分析仪实现的质量选择的质量。新型的产物离子串联质谱（MS/MS）扫描的子类型，称为总和产物离子扫描，用生物化合物混合物进行了演示。它用于在同时隔离和碰撞激活多个前体物种后，即处于不同电荷状态的相同分析物的离子，对产物离子进行特征描述。总和产物离子扫描可用于增强感兴趣分析物的灵敏度，或提供比监测分析物的单个电离形式更全面的信息。使用简单的药物混合物测试了波形隔离方法的分析性能，并简要探讨了其在制备性质谱中提高总体产率的潜力。结果表明，离子软着陆表面的离子转移效率约为 70%。上限质量范围受到拉伸几何形状引起的轴向加速的限制，对此问题提供了一种解决方案。
