Moradian Annie, Douglas D J
Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada.
J Am Soc Mass Spectrom. 2008 Feb;19(2):270-80. doi: 10.1016/j.jasms.2007.10.025. Epub 2007 Nov 12.
Mass selective axial ejection of ions from linear quadrupoles with added octopole fields is described. Quadrupoles with 2.0% and 2.6% added octopole fields have been tested and compared with a conventional quadrupole. The effects of trapping ions at different q values, excitation voltage, scan direction, balanced and unbalanced rf voltages on the rods, and dc applied between the rods have been investigated. The highest scan speeds and best resolution are obtained with resonant excitation and ejection at high q (q = 0.8). With axial ejection, the quadrupole with a 2.0% added octopole field provides mass resolution and ejection efficiencies similar to a conventional rod set. Quadrupole, dipole, and simultaneous dipole-dipole excitation between the x and y rod pairs were compared, and no advantage was found with quadrupole or dipole-dipole excitation. The effects of scan speed were investigated and a resolution at half height of about 1600 is possible at scans speed up to 5000 Th/s.
描述了利用添加八极场从线性四极杆中进行质量选择性轴向离子喷射的方法。已对添加了2.0%和2.6%八极场的四极杆进行了测试，并与传统四极杆进行了比较。研究了在不同q值下捕获离子、激发电压、扫描方向、杆上平衡和不平衡射频电压以及杆之间施加的直流电压的影响。在高q值（q = 0.8）下进行共振激发和喷射可获得最高扫描速度和最佳分辨率。通过轴向喷射，添加了2.0%八极场的四极杆提供的质量分辨率和喷射效率与传统杆组相似。比较了x和y杆对之间的四极、偶极以及同时进行的偶极 - 偶极激发，发现四极或偶极 - 偶极激发并无优势。研究了扫描速度的影响，在扫描速度高达5000 Th/s时，半高宽处的分辨率约为1600是可能的。
