Matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry with pulsed in-source collision gas and in-source ion accumulation

148

136

Analytical methods are pursued to measure the identity and location of biomolecules down to the subcellular ( m) level. Available mass spectrometric imaging methods either compromise localization accuracy or identification accuracy in their analysis of surface biomolecules. In this study, imaging FTICR-MS is applied for the spatially resolved mass analysis of rat brain tissue with the aim to optimize protein identification by the high mass accuracy and online MS/MS capabilities of the technique. Mass accuracies up to 6 ppm were obtained in the direct MALDI-analysis of the tissue together with a spatial resolution of 200 m. The spatial distributions of biomolecules differing in mass by less than 0.1 Da could be resolved, and are shown to differ significantly. Online MS/MS analysis of selected ions was demonstrated. A comparison of the FTICR-MS imaging results with stigmatic TOF imaging on the same sample is presented. To reduce the extended measuring times involved, it is recommended to restrict the FTICR-MS analyses to areas of interest as can be preselected by other, faster imaging methods. (J Am Soc Mass Spectrom 2007, 18, 145-151)

Section: Mass Spectrometry Fticr-ms Fticr-ms Experiments Were Performedmentioning

confidence: 99%

Imaging of peptides in the rat brain using MALDI-FTICR mass spectrometry

Taban

Altelaar

Burgt

et al. 2007

148

136

“…Recently, work on MALDI at higher pressures, from 1-10 mbar [34] to 1 bar [35], has demonstrated that the hot MALDI ions can be cooled by desorption in a high pressure bath gas, and recent developments have extended this finding to FTMS at 10 Ϫ2 mbar [36] and at 1-10 mbar [27]. In this study, the recently reported high pressure MALDI-FTMS ion source is investigated with respect to the analysis of these highly labile gangliosides containing up to five sialic acid residues.…”

mentioning

confidence: 99%

High pressure matrix-assisted laser desorption/ionization Fourier transform mass spectrometry for minimization of ganglioside fragmentation

O’Connor

Mirgorodskaya

Costello

2002

Transiently elevating pressure in a matrix-assisted laser desorption/ionization Fourier transform mass spectrometry (MALDI-FTMS) source into the 1-10 mbar range during ionization decreases the metastable fragmentation of gangliosides. This allows detection of the molecular ion species without loss of the highly labile sialic acid residues. In these experiments, gangliosides with up to five sialic acids were ionized by MALDI and detected with the FTMS. In each case, when the high pressure collisional cooling was used, the singly charged molecular ion was the base peak in the spectra, both in the positive and negative ion modes, and minimal metastable fragmentation was observed. This result is promising, as the previously developed TLC separation methods can be coupled to MALDI-FTMS. (J Am Soc Mass Spectrom 2002, 13, 402-407)

“…The construction details of the MALDI source used in this paper have been described in detail elsewhere [36]. Further improvement of the source includes a 100 spot target (10 ϫ 10 geometry), which can be moved in the xy-plane by software control.…”

Section: Apparatusmentioning

confidence: 99%

“…The MALDI source with a hexapole ion guide that was originally designed to incorporate pulsed gas to collisionally cool ions (Baykut, G.;Jertz, R.; Witt, M. Rapid Commun. Mass Spectrom.…”

mentioning

confidence: 99%

See 1 more Smart Citation

In-source H/D exchange and ion-molecule reactions using matrix assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry with pulsed collision and reaction gases

Witt

Fuchser

Baykut

2002

Self Cite

Controlled in-source ion-molecule reactions are performed for the first time in an external matrix assisted laser desorption ionization (MALDI) source of a Fourier transform ion cyclotron resonance mass spectrometer. The MALDI source with a hexapole ion guide that was originally designed to incorporate pulsed gas to collisionally cool ions (Baykut, G.;Jertz, R.; Witt, M. Rapid Commun. Mass Spectrom. 2000, 14, 1238 -1247 has been modified to allow the study of in-source ion-molecule reactions. Upon laser desorption, a reaction gas was introduced through a second inlet and allowed to interact with the MALDI-generated ions trapped in the hexapole ion guide. Performing ion-molecule reactions in the high pressure range of the ion source prior to analysis in the ion cyclotron resonance (ICR) cell allows to maintain the ultra high vacuum in the cell which is crucial for high mass resolution measurements. In addition, due to the reaction gas pressure in the hexapole product ion formation is much faster than would be otherwise possible in the ICR cell. H/D exchange reactions with different peptides are investigated, as are proton-bound complex formations. A typical experimental sequence would be ion accumulation in the hexapole ion guide from multiple laser shots, addition of cooling gas during ion formation, addition of reaction gas, varied time delays for the ion-molecule reactions, and transmission of the product ions into the ICR cell for mass analysis. In this MALDI source H/D exchange reactions for different protonated peptides are investigated, as well as proton-bound complex formations with the reaction gas triethylamine. Amino acid sequence, structural flexibility and folding state of the peptides can be seen to play a part in the reactivity of such ions. [1-5] and matrix assisted laser desorption ionization (MALDI) [6 -9] has provided mass spectrometry (MS) with two very important tools for investigating biomolecules in the gas phase. ESI and MALDI are fairly mild ionization processes, generally involving cation transfer (usually a proton), that generates positive or negative gas-phase ions while retaining the structural integrity of the analyte. More and more structural information of peptides is emerging from gas-phase studies utilizing mass spectrometry.MALDI has become one of the fastest growing techniques in mass spectrometry due to its application to biological and biochemical research [9 -14]. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) [15][16][17][18][19][20] is known for its unparalleled mass accuracy and mass resolution and has become an important tool in many areas of analytical life sciences [21,22]. For this reason, the FT-ICR MS technique has been combined with the soft ionization technique MALDI using internal [23][24][25][26][27][28] as well as external [29 -37] ion sources. One of the striking advantages of the MALDI FT-ICR technique is high sensitivity as well as high throughput capability.Many ion chemistry studies show similarities between the behavior of gas-...