Post source decay

In linear quadmpoles the CID activation time is equal to the time the accelerated precursor ion ( 100 eV) takes to pass through the collision cell. The primary fragments produced will continue to undergo collisions that cause them to fragment as well, and so on, thus producing richer and more complex fragment-ion spectra. 

In the ion cyclotron resonance (ICR) cell CID is performed by resonant excitation of the precursor ion and subsequent collisions with the background gas. One serious drawback with on-resonance excitation in the ICR cell is that the risk for ion losses due to 

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Matrix-assisted laser desorption ionization post-source-decay mass spectrometry... 

In instrnments withont a reflectron (see Figure 3.7 above), both the precursor and prodnct ions reach the detector at the same time and are not separated. The reflectron, however, is an energy analyser and product ions with different energies, after passage through the reflectron, will have different flight times to the detector and may be separated and their m/z ratios determined. This is known as post-source decay (PSD) [11]. 

Experimentation showed that the protein was not glycosylated and that the sequence at the iV-amino acid terminus corresponded to that expected. The C-terminus sequence, however, did not correspond to that predicted and these data were interpreted in terms of the presence of a heterogeneous, truncated, protein. A study of the tryptic digest fragments from this protein with matrix-assisted laser desorption ionization (MALDI) with post-source decay enabled the authors to suggest the positions at which the parent protein had been truncated. 

Post-source decay The term used to describe the production of product-ion MS-MS spectra in a time-of-flight mass analyser. 

Post-source decay RT.TF Remote laser-induced fluorescence... 

Both collisional activation (in ion traps) and post source decay (in curved field reflectron TOF analyzers) have been used successfully to obtain sequence ions from peptides prepared in situ on the sample holder. Single Dalton mass windows are advantageous for precursor selection, as are realized in ion-trap and trap-TOF configurations. Publicly available search algorithms can be used... 

Figure 6 Partial MALDI-TOF mass spectrum from PMMA generated by ATRP with ethyl-2-bromoisobutyrate as initiator (inset shows theoretical isotope distribution for lithiated 18-mer of structure 3). (Peak labelled 3 arises from post-source decay of 3 [10].)...

B. Spengler. Post-Source Decay Analysis in Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry of Biomolecules. J. Mass Spectrom., 32(1997) 1019-1036. 

The development glycopeptide libraries obtained by the split-mix method is severely hampered by the lack of concurrent development of a general, facile separation and characterization technology. Some headway has been made with chemical coding of the libraries, but very few direct methods of analysis exist. One promising method that could be applied to the direct characterization of both types of libraries is mass spectrometry. More specifically, post-source-decay matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (PSD-MALDI-TOF-MS) and CID-FAB/MS/MS have been used to characterize glycopeptides.53-55... 

PAGE Phe Pro PSD QC Q-ToF Q-ToF-LC-MS-MS polyacrylamide gel electrophoresis phenylalanine proline post-source decay quality control quadrupole time-of-flight mass analyser quadrupole time-of-flight mass analyser in combination with (high performance) liquid chromatography and tandem mass... 

Several original papers must be mentioned that deal with mass spectrometric techniques which the numerous reviews do not comprise. Kaufmann and coworkers268,288 studied the mass spectrometric analysis of carotenoids and some of their fatty acid esters using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry and its post-source-decay (PSD) variant. Some advantages concerning the thermal instability and limited solubility were discussed, but the fragmentation paths of the carotenoid cations were found to be essentially the same as those observed with conventional techniques. 

Note In particular the MALDI-TOF community has coined some sort of an own terminology, e.g., in-source decay (ISD) for all fragmentations occurring within the ion source, post-source decay (PSD) instead of metastable ion dissociation and fragment analysis and structural TOF (FAST) for the specific mode of operation of a ReTOF to detect metastable ions. 

Cordero, M.M. Cornish, T.J. Cotter, R.J. Lys, LA. Sequencing Peptides Without Scanning the Reflectron Post-Source Decay With a Curved-Field Reflectron TOF Spectrometer. Rapid Commun. Mass Spectrom. 1995, 9, 1356-1361. 

Spengler B (2001) The basics of matrix-assisted laser desorption ionization time-of flight mass spectrometry and post source decay. In James P (ed) (2001) Proteome research Mass spectrometry. Springer, New York, p 33... 

Keki, S., Deak, G., and Zsuga, M., Fragmentation study of rutin, a naturally occurring flavone glycoside cationized with different alkali metal ions, using post-source decay matrix-assisted laser desorption/ionization mass spectrometry, J. Mass Spectrom., 36, 1312, 2001. 

Kaufmann, R., Wingerath, T., Kirsch, D., Stahl, W., and Sies, H. 1996. Analysis of carotenoids and carotenol fatty acid esters by matrix-assisted laser desorption ionization (MALDI) and MALDI-post-source-decay mass spectrometry. Anal. Biochem. 238 117-128. 

Peptide sequencing via post-source decay and tandem mass spectrometry. 339... 

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