Xia Yu, Thomson Bruce A, McLuckey Scott A
Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, USA.
Anal Chem. 2007 Nov 1;79(21):8199-206. doi: 10.1021/ac071448m. Epub 2007 Oct 3.
Methods for bidirectional ion transmission between distinct quadrupole arrays were developed on a quadrupole/time-of-flight tandem mass spectrometer (QqTOF) containing three quadrupoles (ion guide Q0, mass filter Q1, and collision cell Q2) and a reflectron TOF analyzer, for the purpose of implementing multistage ion/ion reaction experiments. The transfer efficiency, defined as the percentage of ions detected after two transfer steps relative to the initial ion abundance, was found to be about 60% between Q2 and Q0 (with passage through the intermediate array (Q1)) and almost 100% between Q2 and Q1. Efficient ion transfer enabled new means for executing MSn experiments on an instrument of this type by operating Q1 in rf/dc mode for performing multiple steps of precursor/product ion isolation while passing ions through Q1 or trapping ions in Q1. In the latter case, the Q1 functioned as a linear ion trap. Either collision induced dissociation (CID) or ion/ion reactions can be conducted in between each stage of mass analysis. MS3 or MS4 experiments were developed to illustrate the charge increase of peptide ions via two steps of charge inversion ion/ion reactions, CID of electron-transfer dissociation (ETD) products and CID of a metal-peptide complex formed from ion/ion reactions.
在一台包含三个四极杆（离子导向器Q0、质量过滤器Q1和碰撞池Q2）以及一个反射式飞行时间分析仪的四极杆/飞行时间串联质谱仪（QqTOF）上，开发了不同四极杆阵列之间双向离子传输的方法，以实现多级离子/离子反应实验。传输效率定义为经过两步传输后检测到的离子数相对于初始离子丰度的百分比，发现在Q2和Q0之间（经过中间阵列（Q1））约为60%，在Q2和Q1之间几乎为100%。高效的离子传输通过在rf/dc模式下操作Q1，在前体/产物离子分离的多个步骤中使离子通过Q1或在Q1中捕获离子，从而为在这种类型的仪器上进行MSn实验提供了新方法。在后一种情况下，Q1起到线性离子阱的作用。在质量分析的每个阶段之间，可以进行碰撞诱导解离（CID）或离子/离子反应。开发了MS3或MS4实验，以说明通过两步电荷反转离子/离子反应、电子转移解离（ETD）产物的CID以及由离子/离子反应形成的金属 - 肽络合物的CID来增加肽离子的电荷。
