Department of Chemistry and Center for Analytical Instrumentation Development, Purdue University, West Lafayette, IN, 47907, USA.
J Am Soc Mass Spectrom. 2016 Dec;27(12):1922-1928. doi: 10.1007/s13361-016-1473-2. Epub 2016 Sep 6.
The use of successive resonances for ion ejection is demonstrated here as a method of scanning quadrupole ion traps with improvement in both resolution and sensitivity compared with single frequency resonance ejection. The conventional single frequency resonance ejection waveform is replaced with a dual-frequency waveform. The two included frequencies are spaced very closely and their relative amplitudes are adjusted so that the first frequency that ions encounter excites them to higher amplitudes where space charge effects are less prominent, thereby giving faster and more efficient ejection when the ions come into resonance with the second frequency. The method is applicable at any arbitrary frequency, unlike double and triple resonance methods. However, like double and triple resonance ejection, ejection using successive resonances requires the rf and AC waveforms to be phase-locked in order to retain mass accuracy and mass precision. The improved performance is seen in mass spectra acquired by rf amplitude scans (resonance ejection) as well as by secular frequency scans. Graphical Abstract ᅟ.
这里展示了利用连续共振进行离子引出的方法，与单频共振引出相比，该方法可提高分辨率和灵敏度。用双频波形代替传统的单频共振引出波形。两个包含的频率间隔非常近，并且它们的相对幅度进行了调整，使得离子遇到的第一个频率将它们激发到更高的幅度，在那里空间电荷效应不那么明显，从而在离子与第二个频率共振时实现更快、更有效的引出。与双共振和三共振方法不同，该方法可在任意频率下使用。然而，与双共振和三共振引出一样，使用连续共振需要将射频和交流波形进行锁定相位，以保持质量准确度和质量精度。在通过射频幅度扫描（共振引出）和 secular 频率扫描获得的质谱中都可以看到改进的性能。
