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    Tandem Mass Spectrometry in an Electrostatic Linear Ion Trap Modified for Surface-Induced Dissociation
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    Abstract:
    A variety of ion traps are used in mass spectrometry. A key feature shared by most of them is the ability to perform tandem mass spectrometry (MS/MS). The Orbitrap is perhaps the most notable ion trap in which MS/MS has yet to be performed. An electrostatic linear ion trap (ELIT) is analogous to an orbitrap in that ions are trapped using solely electrostatic fields. However, the relatively simple ion motion within an ELIT facilitates analysis of fragment ions produced within the device. In this report, we describe an ELIT to which we have added a target for surface induced dissociation (SID). When combined with our previously described method for isolating a precursor ion trapped in an ELIT,1 this apparatus enables MS/MS to be performed. Measurement of product ion m/z is facilitated by the fact that the ELIT is isochronous over the energy range of 1850-2000 eV so that changes to ion energy during SID do not cause major m/z shifts. We demonstrate MS/MS by isolating and dissociating each compound in a four component mixture of tetraalkylphosphonium cations. We also discuss the optimization of collision energy and the length of time that the SID target is available for collision, two parameters that are important in the performance of these experiments.
    Keywords:
    Orbitrap
    Quadrupole ion trap
    Collision-induced dissociation
    Tandem
    Penning trap
    A novel mass spectrometric imaging method is developed to reduce the data acquisition time and provide rich chemical information using a hybrid linear ion trap−orbitrap mass spectrometer. In this method, the linear ion trap and orbitrap are used in tandem to reduce the acquisition time by incorporating multiple linear ion trap scans during an orbitrap scan utilizing a spiral raster step plate movement. The data acquisition time was decreased by 43−49% in the current experiment compared to that of orbitrap-only scans; however, 75% or more time could be saved for higher mass resolution and with a higher repetition rate laser. Using this approach, a high spatial resolution of 10 μm was maintained at ion trap imaging, while orbitrap spectra were acquired at a lower spatial resolution, 20−40 μm, all with far less data acquisition time. Furthermore, various MS imaging methods were developed by interspersing MS/MS and MSn ion trap scans during orbitrap scans to provide more analytical information on the sample. This method was applied to differentiate and localize structural isomers of several flavonol glycosides from an Arabidopsis flower petal in which MS/MS, MSn, ion trap, and orbitrap images were all acquired in a single data acquisition.
    Orbitrap
    Quadrupole ion trap
    Hybrid mass spectrometer
    Trap (plumbing)
    Citations (84)
    Quadrupole ion trap
    Orbitrap
    Hybrid mass spectrometer
    Quadrupole mass analyzer
    MALDI imaging
    Trap (plumbing)
    Ion trapping
    Citations (0)
    Abstract The aim of this study was to investigate the fragmentation behavior induced by low‐energy collision‐induced dissociation (LE‐CID) of four selected antioxidants applied in lubricants, by two different types of ion trap mass spectrometers: a three‐dimensional ion trap (3D‐IT) and a linear IT (LIT) Orbitrap MS. Two sterically hindered phenols and two aromatic amines were selected as model compounds representing different antioxidant classes and were characterized by positive‐ion electrospray ionization (ESI) and LE‐CID. Various types of molecular ions (e.g. [M] +• , [M + H] + , [M + NH 4 ] + or [M + Na] + ) were used as precursor ions generating a significant number of structurally relevant product ions. Furthermore, the phenolic compounds were analyzed by negative‐ion ESI. For both IT types applied for fragmentation, the antioxidants exhibited the same unusual LE‐CID behavior: (1) they formed stable radical product ions and (2) CC bond cleavages of aliphatic substituents were observed and their respective cleavage sites depended on the precursor ion selected. This fragmentation provided information on the type of structural isomer usually not obtainable for branched aliphatic substituents utilizing LE‐CID. Comparing the two instruments, the main benefit of applying the LIT‐Orbitrap was direct access to elemental composition of product ions enabling unambiguous interpretation of fragmentation trees not obtainable by the 3D‐IT device (e.g. loss of isobaric neutrals). It should be emphasized that the types of product ions formed do not depend on the type of IT analyzer applied. For characterizing degradation products of antioxidants, the LIT‐Orbitrap hybrid system, allowing the determination of accurate m / z values for product ions, is the method of choice. Copyright © 2011 John Wiley & Sons, Ltd.
    Orbitrap
    Quadrupole ion trap
    Fragmentation
    Collision-induced dissociation
    Citations (13)
    Ion traps like the Orbitrap are well known mass analyzers with very high resolving power. This resolving power is achieved with help of ions orbiting around an inner electrode for long time, in general up to a few seconds, since the mass signal is obtained by calculating the Fourier Transform of the induced signal caused by the ion motion. A similar principle is applied in the Cassinian Ion Trap of second order, where the ions move in a periodic pattern in-between two inner electrodes. The Cassinian ion trap has the potential to offer mass resolving power comparable to the Orbitrap with advantages regarding the experimental implementation. In this paper we have investigated the details of the ion motion analyzing experimental data and the results of different numerical methods, with focus on increasing the resolving power by increasing the oscillation frequency for ions in a high field ion trap. In this context the influence of the trap door, a tunnel through which the ions are injected into the trap, on the ion velocity becomes especially important.
    Orbitrap
    Quadrupole ion trap
    Trap (plumbing)
    Oscillation (cell signaling)
    Ion trapping
    Citations (3)