Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, United States.
Anal Chem. 2013 May 21;85(10):5226-32. doi: 10.1021/ac4007182. Epub 2013 Apr 30.
A novel hybrid tandem mass spectrometer is presented that combines a linear quadrupole ion trap (QLIT) with a linear electrostatic ion trap (ELIT), which is composed of opposing ion mirrors. The QLIT is used both as an accumulation device for the pulsed injection of ions into the ELIT and as a collision cell for ions released from the ELIT and back into the QLIT. Ions are subjected to mass analysis in the ELIT via Fourier transformation of the time-domain signal obtained from an image current measurement using a pick-up electrode in the field-free region of the ELIT. The nondestructive nature of ion detection and the relatively straightforward axial entrance and exit of ions into and from the ELIT allow for the execution of nondestructive tandem mass spectrometry experiments whereby both the initial mass spectrum and the product ion spectrum are obtained on the same initial ion population. The timed pulsing of a deflection electrode, in conjunction with the release of ions from the ELIT, allows for the selection of precursor ions for recapture by the QLIT. The transfer of ions back and forth between the QLIT and ELIT is illustrated with Cs ions, the selection of precursor ions is demonstrated with isotopes of tetraoctylammonium cations, and complete nondestructive tandem mass spectrometry experiments are demonstrated with a mixture of angiotensin II and bradykinin cations. With the current apparatus, the efficiency for the process of recapturing ions and then reinjecting them into the ELIT is 35%-40%. The instrument is capable of isolating an ion from a neighbor with a mass as close as 1 part in 500, with negligible loss of the desired species.
提出了一种新型混合串联质谱仪,它将线性四极离子阱(QLIT)与线性静电离子阱(ELIT)相结合,ELIT 由相对的离子镜组成。QLIT 既是脉冲注入离子进入 ELIT 的积累装置,也是从 ELIT 释放并返回到 QLIT 的离子的碰撞室。通过在 ELIT 的无场区中使用拾波电极从图像电流测量中获得的时域信号进行傅里叶变换,在 ELIT 中对离子进行质量分析。由于离子检测的非破坏性以及离子进入和离开 ELIT 的相对简单的轴向入口和出口,因此可以执行非破坏性串联质谱实验,其中初始质谱和产物离子谱都在相同的初始离子群体上获得。与 ELIT 一起释放离子的偏转电极的定时脉冲允许选择用于被 QLIT 重新捕获的前体离子。QLIT 和 ELIT 之间的离子来回转移如图 Cs 离子所示,前体离子的选择用四辛基铵阳离子的同位素证明,用血管紧张素 II 和缓激肽阳离子的混合物证明完整的非破坏性串联质谱实验。使用当前仪器,将离子重新捕获并重新注入 ELIT 的过程的效率为 35%-40%。该仪器能够从质量接近 1 比 500 的邻居中分离出离子,而所需物质的损失可以忽略不计。