Cha B, Blades M, Douglas D J
Department of Chemistry, University of British Columbia, Vancouver, Canada.
Anal Chem. 2000 Nov 15;72(22):5647-54. doi: 10.1021/ac0004862.
A new ion sampling interface for an electrospray ionization 3D ion trap mass spectrometer system is described. The interface uses linear rf quadrupoles as ion guides and ion traps to enhance the performance of the 3D trap. Trapping ions in the linear quadrupoles is demonstrated to improve the duty cycle of the system. Dipolar excitation of ions trapped in a linear quadrupole is used to eject unwanted ions. A resolution of ejection of up to 254 is demonstrated for protonated reserpine ions (m/z 609.3). A composite waveform with a notch in frequency space is used to eject a wide range of matrix ions and to isolate trace analyte ions in a linear quadrupole before ions are injected into the 3D trap. This is useful to overcome space charge problems in the 3D trap caused by excess matrix ions. For trace reserpine in a 500-fold molar excess of poly(propylene glycol) (PPG), it is demonstrated that the resolution and sensitivity of the 3D trap can be increased dramatically with ejection of the excess PPG matrix ions. In comparison to ejection of matrix ions in the 3D trap with a similar broad-band waveform, a 5-fold increase in sensitivity with a 7 times shorter acquisition time was achieved.
描述了一种用于电喷雾电离三维离子阱质谱仪系统的新型离子采样接口。该接口使用线性射频四极杆作为离子导向器和离子阱，以提高三维阱的性能。已证明在线性四极杆中捕获离子可改善系统的占空比。利用线性四极杆中捕获离子的偶极激发来逐出不需要的离子。对于质子化利血平离子（m/z 609.3），逐出分辨率高达254。频率空间中带有陷波的复合波形用于逐出各种基质离子，并在线性四极杆中将痕量分析物离子分离出来，然后再将离子注入三维阱中。这对于克服由过量基质离子导致的三维阱中的空间电荷问题很有用。对于在500倍摩尔过量的聚丙二醇（PPG）中的痕量利血平，已证明通过逐出过量的PPG基质离子，三维阱的分辨率和灵敏度可显著提高。与使用类似宽带波形在三维阱中逐出基质离子相比，灵敏度提高了5倍，采集时间缩短了7倍。
