LETTER pubs.acs.org/ac
Nondestructive Ion Trap Mass Analysis at High Pressure Wei Xu,† Jeffrey B. Maas,‡ Frank J. Boudreau,§ William J. Chappell,‡ and Zheng Ouyang*,†,‡,§ †
Weldon School of Biomedical Engineering, ‡Department of Electrical and Computer Engineering, and §Center for Analytical Instrumentation Development, Purdue University, West Lafayette, Indiana 47907, United States
bS Supporting Information ABSTRACT:
A method for performing nondestructive ion trap mass analysis at high pressures (>1 mTorr) has been developed using image current measurement with constant dipolar excitation. Instead of monitoring the ion secular motion, a harmonic of the ion motion was used for narrow band image current measurement followed by Fourier Transform. The capability of this technique has been demonstrated with mass analysis using a single measurement at pressures of 10 mTorr or higher. Methods for mixture analysis and tandem mass spectrometry have also been developed for nondestructive mass analysis.
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uadrupole ion trap mass spectrometry is a sensitive and versatile method for chemical analysis.1,2 Ion traps are popular ion storage and mass analysis devices for stand-alone as well as hybrid mass spectrometers. Of all the mass analyzers, the quadrupole ion trap mass analyzer has unique features including relatively high pressure mass analysis and multistage tandem mass spectrometry (MS/MS) using a single analyzer.3-6 This makes the ion trap a powerful candidate for the mass analyzer in miniaturized instruments.7-12 The typical method for mass analysis using ion traps is to eject ions in order of their massto-charge ratios (m/z) for ion detection. Various procedures have been developed for this implementation, including the mass-selective instability scan with RF amplitude scan13,14 and resonance ejection with frequency scans,11,15 etc. In comparison with these destructive ion-detection methods, nondestructive mass analysis using image current measurement is used in Fourier transform ion cyclotron resonance (FTICR)16-19 and orbitrap mass spectrometers.20-22 High resolution is achieved for mass analysis with measurement of the ion motions in ultrahigh vacuum (
