Konenkov Nikolai, Zhao Xianzhen, Xiao Zilan, Douglas D J
Department of General Physics, Ryazan State Pedagogical University, Ryazan, Russia.
J Am Soc Mass Spectrom. 2007 May;18(5):826-34. doi: 10.1016/j.jasms.2007.01.002. Epub 2007 Mar 2.
Mass analysis with linear quadrupole mass filters is possible by forming "islands" in the stability diagram with auxiliary quadrupole excitation. In this work, computer simulations are used to calculate stability boundaries, island positions, and peak shapes and ion transmission for mass analysis with linear quadrupole mass filters that have added octopole fields of about 2 to 4%. Rod sets with exact geometries that have quadrupole and octopole fields only in the potential, and round rod sets, with multipoles up to N = 10 (the twenty pole term) included in the calculations, show the same stability boundaries, island positions, and peak shapes. With the DC voltage applied to the rods so that the Mathieu parameter a < 0, conventional mass analysis is possible without the use of an island. With the DC polarity reversed so that a > 0, the resolution and transmission are poor preventing conventional mass analysis. In principle, mass analysis in an island is possible with operation at either of two tips. Provided the correct island tip is chosen for mass analysis, peak shapes comparable to those with a > 0 and no excitation are possible, both with a > 0 and with a < 0. In the latter case, the use of an island of stability allows mass analysis when the added octopole otherwise prevents conventional mass analysis.
通过在稳定性图中利用辅助四极杆激发形成“岛”，使用线性四极杆质量分析器进行质量分析是可行的。在这项工作中，计算机模拟用于计算稳定性边界、岛的位置、峰形以及使用添加了约2%至4%八极场的线性四极杆质量分析器进行质量分析时的离子传输情况。仅在电势中具有四极和八极场的精确几何形状的杆组，以及在计算中包含高达N = 10（二十极项）的多极的圆形杆组，显示出相同的稳定性边界、岛的位置和峰形。当向杆施加直流电压使得Mathieu参数a < 0时，无需使用岛即可进行常规质量分析。当直流极性反转使得a > 0时，分辨率和传输较差，无法进行常规质量分析。原则上，在岛的两个尖端之一进行操作时，在岛中进行质量分析是可行的。只要为质量分析选择正确的岛尖端，对于a > 0和a < 0的情况，都可以获得与a > 0且无激发时相当的峰形。在后一种情况下，当添加的八极场否则会阻止常规质量分析时，使用稳定性岛可实现质量分析。
