QIT-TOF Mass Spectrometers

Baba, T. Black, D. Glish, G.L. ECD coupled with a linear RF QIT-TOF mass spectrometer. 51st ASMS Conference on Mass Spectrometry and Allied Topics. June 8-12, 2003. Montreal, Canada. 

Molecular identification was performed with tandem mass spectrometry using a QIT-TOF mass spectrometer (AXIMA-QIT Shimadzu, Kyoto, Japan) to ensure the molecular assignment which was performed using only mass. The MS analysis was performed directly on the sections of tissue sections in the mid-mass range mode. 

The highest sensitivity (mol/well) is shown for each analysis when 1 pmol - 1 fmol/well analytes were analyzed using MALDI-QIT-TOF mass spectrometer. ND denotes that analyte molecular ions are not... 

Fig. 7. Positive and negative ion mass spectra of Analyte-5 (100 fmol/well) with DHB (A and D), G2CHCA (B and E) and G3CA (C and F) using MALDI-QIT-TOF mass spectrometer. Dissociation of N-acetylneuraminic acid (NANA sialic add) was suppressed using G2CHCA or G3CA (B, C, E and F).

Shimma S, Furuta M, Ichimura K. A novel approach to in situ proteome analysis using a chemical inkjet printing technology and MALDI-QIT-TOF tandem mass spectrometer. J. Mass. Spectrom. Soc. Jpn. 2006 54 133-140. 

Tandem Mass Spectrometer An instrument capable of performing multiple mass (mjz) analyses. There are two major categories (1) tandem-in-space instruments (triple quadmpole and Q-TOF), (2) tandem-in-time instruments (QIT and FTICR). 

The role of the mass analyzer is to separate ions according to their miz values and to focus and transfer these ions onto a detector, or into a collision cell in multianalyzer instruments (see later). The mass analyzer is the heart of all mass spectrometers (block 3 in Figure 1.2). The choice of which analyzer to use is critical as it affects multiple aspects of the data generated, including mass resolution, mass measurement accuracy, and available dynamic range. There are several types of analyzer quadru-pole (Q), ion trap (quadrupole (QIT) or linear (LIT) ion trap), time-of-flight (TOF),... 

Once ions have been formed, either outside the mass spectrometer using API methods or within the vacuum system by El, Cl, or MALDI, the ions must be separated according to their m/z ratios. There are several types of mass analyzer with significantly different modes of operation, but all separate ions according to their miz ratios, so that these ratios and their intensities can be recorded by the detector. Current mass analyzers include quadrupole (Q), quadrupole ion traps (QIT, LIT), Fourier transformed based (FT), time-of-flight (TOF), and to a much lesser extent, magnetic field (B). 

The fundamental process of MS/MS (in a tandem mass spectrometer) is that a particular precursor ion is fragmented (decomposed) into a smaller product ion accompanied by the loss of a neutral fragment. The precursor ion is usually selected in the first analyzer, reacted by some means in a specialized chamber (see below) to produce product ions that are then separated in a second analyzer, hence the terms mass spectrometry/mass spectrometry and tandem mass spectrometry. As discussed later, precmsor and product ion analyses can be separated in space, using sequential analyzers that are either of the same type or in hybrid configurations, or separated in time in the latter the two analytical processes are carried out sequentially, within the same analyzer. There are several MS/MS instrument combinations, including QqQ, QIT, LIT, TOF/TOF, QTOF, LlT-orbitrap, and LIT-FT-ICRMS. 

Fig. 5. Representative peptide mass fingerprint for the 33.2 and 66.6 kDa proteins resulting from an in-gel digestion of the 66.6 kDa gel band obtained by MALDI-TOF mass spectrometry. Peptides marked with an asterisk result from autodigestion products of recombinant trypsin. Peptides labeled with a diamond were selected for MS/MS experiments carried out on a MALDI-QIT/RTOF and a nano-ESI-QIT mass spectrometer.

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