Whalen K, Grossert J S, Boyd R K
Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, Canada.
Rapid Commun Mass Spectrom. 1995;9(14):1366-75. doi: 10.1002/rcm.1290091409.
This work concerns a new high-pressure quadrupole collision cell, designed for triple-quadrupole mass spectrometers. This new collision cell operates at pressures up to 10 mTorr, an order of magnitude higher than conventional cells of this type. Previous investigations have concentrated upon the significant increases in transmission efficiency and in resolving power for fragment ions which result from the use of this new design. The present work reports an investigation into the nature of the dissociation reactions which can be induced by collisions in this high-pressure cell. Charge-site-remote fragmentations of a simple precursor ion were chosen as a test case, and were found to be observable at laboratory collision energies lower by a factor of 4-5 than those found previously to be necessary when using conventional low-pressure quadrupole collision cells. It was also shown that the charge-site-remote reactions were accompanied by the mixed-site-fragmentation reactions described by Tuinman and Cook (J. Am. Soc. Mass Spectrom. Vol. 1, p. 85 (1989)). Ionization of collision gas was observed in the case of xenon. Efforts to observe charge-site-remote fragmentations of peptide ions were marginally successful. Highly basic peptides, which have been problematic for sequencing by low-energy tandem mass spectrometry, did not yield useful fragment-ion spectra in the new cell. The fragmentation behaviour of protonated Leu-enkephalin, for which fragmentation pathways have been thoroughly studied previously, suggested that the observed spectra reflected integration of the fragmentation kinetics over a considerably longer time, thus involving many more reaction steps. These combined observations are considered in terms of a qualitative model based on a rapid decrease of ion kinetic energy during passage through the cell, with much longer residence times than for conventional quadrupole cells.
这项工作涉及一种为三重四极杆质谱仪设计的新型高压四极杆碰撞池。这种新型碰撞池的工作压力高达10毫托，比此类传统碰撞池高一个数量级。先前的研究集中于使用这种新设计后，碎片离子的传输效率和分辨率有显著提高。目前的工作报道了对这种高压碰撞池中碰撞所引发的解离反应性质的研究。选择一种简单前体离子的电荷位点远程碎片化作为测试案例，发现其在实验室碰撞能量下比使用传统低压四极杆碰撞池时所需的能量低4至5倍时仍可观测到。研究还表明，电荷位点远程反应伴随着Tuinman和Cook（《美国质谱学会杂志》第1卷，第85页（1989年））所描述的混合位点碎片化反应。在氙气的情况下观察到了碰撞气体的电离。观察肽离子电荷位点远程碎片化的努力取得了一定成功。对于低能量串联质谱测序存在问题的高碱性肽，在新碰撞池中未产生有用的碎片离子谱。此前已对其碎片化途径进行了深入研究的质子化亮氨酸脑啡肽的碎片化行为表明，所观察到的谱图反映了在相当长的时间内碎片化动力学的积分，因此涉及更多的反应步骤。基于离子在通过碰撞池时动能迅速降低且停留时间比传统四极杆碰撞池长得多的定性模型，对这些综合观察结果进行了探讨。
