Extraction delayed

State-of-the-art ToF-MS employs reflection lenses and delayed extraction [176] to improve resolution by minimising small differences in ion energies, and in these cases up to 12000 mass resolution (FWHM, m/z 600) is available. This is sufficient for most modern applications. Solid probe ToF-MS (or direct inlet high-resolution mass spectrometry, DI-HRMS) is a breakthrough. DIP-ToFMS is a thermal separation technique. Advantages of DIP-ToFMS are ... 

Applications MALDI-ToFMS is at its best as a rapid screening technique for quick identification of known additives. However, this screening is rendered slightly more complicated by the fact that MALDI-ToFMS spectra of pure additives and of additives in the presence of excess macromolecules are not always identical (matrix effect) [55]. For unknown additives, the relation MALDI-ToFMS spectrum-chemical structure is not easily established, and the use of FD or MALDI-MS/MS is then needed. As MALDI-MS shows a sensitivity difference for the various additives, it cannot easily quantify them unless the analytes are very similar. For differentiation of additives with the same mass number (e.g. Tinuvin 315 and Cyasorb UV3638 with m/z = 368) high resolution is required, as provided by delayed extraction MALDI-ToFMS. 

Vestal, M. L. Juhasz, R Martin, S. A. Delayed extraction matrix-assisted laser desorption time-of-flight mass spectrometry. Rapid Comm. Mass Spectrom. 1995, 9, 1044-1050. 

The key to the good resolution of ZEKE-PFI is in its discrimination against electrons with >1 cm-1 kinetic energy. This is due to the delayed extraction and time-gated detection. A bubble of 1 cm"1 electrons expands to a radius of 1.6 cm during the 2.0 ps delay. Such kinetic electrons either miss the detector or arrive... 

S.T. Hsiao, M.C. Tseng, Y.R. Chen and G.R. Her, Analysis of polymer additives by matrix-assisted laser desorption ionisation/time of flight mass spectrometer using delayed extraction and collision induced dissociation, J. Chinese Chem. Soc., 48 (2001) 1017-1027. 

M.L. Vestal, P. Juhasz, and S.A. Martin, Delayed Extraction Matrix assisted Laser Desorption Time of flight Mass Spectrometry, Rapid Commun. Mass Spectrom., 9, 1044 1050 (1995). 

JENSEN, O.N., PODTELEJNKOV, A., MATTHIAS-MANN, M., Delayed extraction improves specificity in database searches by matrix-assisted laser desorption/ionization peptide maps, Rapid Comm. Mass Spectrom., 1996,10, 1371-1378. 

DGE a AC AMS APCI API AP-MALDI APPI ASAP BIRD c CAD CE CF CF-FAB Cl CID cw CZE Da DAPCI DART DC DE DESI DIOS DTIMS EC ECD El ELDI EM ESI ETD eV f FAB FAIMS FD FI FT FTICR two-dimensional gel electrophoresis atto, 10 18 alternating current accelerator mass spectrometry atmospheric pressure chemical ionization atmospheric pressure ionization atmospheric pressure matrix-assisted laser desorption/ionization atmospheric pressure photoionization atmospheric-pressure solids analysis probe blackbody infrared radiative dissociation centi, 10-2 collision-activated dissociation capillary electrophoresis continuous flow continuous flow fast atom bombardment chemical ionization collision-induced dissociation continuous wave capillary zone electrophoresis dalton desorption atmospheric pressure chemical ionization direct analysis in real time direct current delayed extraction desorption electrospray ionization desorption/ionization on silicon drift tube ion mobility spectrometry electrochromatography electron capture dissociation electron ionization electrospray-assisted laser desorption/ionization electron multiplier electrospray ionization electron transfer dissociation electron volt femto, 1CT15 fast atom bombardment field asymmetric waveform ion mobility spectrometry field desorption field ionization Fourier transform Fourier transform ion cyclotron resonance... 

Time Focusing Devices. The resolution of the TOF analyzer is limited by the initial velocity spread of the ions. However, there are powerful devices that can compensate for this velocity distribution, and the most widespread techniques at present are the electrostatic ion reflector (electrostatic mirror) and time-lag focusing (delayed extraction). 

Some spectrometers are equipped with delayed extraction. Ions are accelerated from the target only 200 to 300 nsec after the laser beam hits the target. During the short delay, light matrix ions dissipate. This helps to avoid massive collisions during the acceleration between the large molecules and the matrix ions. 

Reflectron time-of-flight mass spectrometers can be used to generate fragment spectra. Before the introduction of delayed extraction, it was observed that the ions had a tendency to disassemble into fragments while they were traveling to the reflectron (Spengler et al., 1992). This behavior is called postsource decay (PSD). The ions collide with matrix ions in the gas phase when they are accelerated with several kilovolts. Their decay occurs in the first field-free drift region. 

Note Unfortunately, establishing patents and trademarks has caused redundant names for almost the same thing Time Lag Focusing (TLF, Micromass) Delayed Extraction (DE, Applied Biosystems) Pulsed Ion Extraction (PIE, Bru-ker Daltonik). 

Juhasz, P. Vestal, M.L. Martin, S.A. On the Initial Velocity of Ions Generated by MALDI and Its Effect on the Calibration of Delayed Extraction-TOF Mass Spectra. 

Recent developments in delayed extraction TOF allow higher resolving power and mass accuracy. The analysis is relatively insensitive to contaminants. 

Recent developments in delayed extraction TOF allow higher resolving power and mass accuracy, and this method in the reflector mode has been used for accurate measurement of the mass of several compounds including two prenylated flavonoids. However, the performance of the MALDI-TOF instrument was not better than those of the FAB and FT-ICR MS instruments, and insufficient to give acceptable accuracy for literature reporting. 

Despite the use of balancing mechanisms of ion extraction, for example, delayed extraction, larger inhomogeneities frequently found in slowly grown crystalline matrix preparations are known to influence the mass accuracies. The highly homogeneous sample surfaces achievable in ILMs can drastically reduce these problems upon conversion of the crystalline matrices into ILMs [45]. 

Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometer with UV laser (i.e., 337-nm nitrogen laser), MALDI probe, and optional delayed extraction and postsource decay... 

Abundant molecular ions, M+, will be observed as the base peaks in the MALDI-TOF mass spectra. Delayed extraction will enhance the abundance of the molecular ions relative to background noise, and the use of postsource decay will facilitate the detection of structurally... 

Figure 5-5. A. MALDI mass spectrum of the anthocyanin pigments in the grape variety Marechal Foch. This figure is from the article Matrix-assisted laser desorption ionization mass spectrometry analysis of grape anthocyanins , Am. J. Enol. Vitic. 50 199-203 by Sugui, J. A., Wood, K. V., Yang, Z., Bonham, C. C. and Nicholson, R. L. 1999. Reprinted by permission of the American Society for Enology and Viticulture. B. MALDI mass spectrum of grape anthocyanins acquired on a MALDI mass spectrometer with delayed extraction capabilities. Peak identities are discussed in the text.

T. Fujiwaki, M. Tasaka, N. Takahashi, H. Kobayashi, Y. Murakami, T. Shimada, and S. Yamaguchi, Quantitative evaluation of sphingolipids using delayed extraction matrix-assisted laser desorption ionization time-of-flight mass spectrometry with sphingosylphosphorylcholine as an internal standard. Practical application to cardiac valves from a patient with Fabry disease, J. Chromatogr. B. 832 (2006) 97-102. 

Haff LA, Smirnov IP. Single-nucleotide polymorphism identification assays using a thermostable DNA polymerase and delayed extraction MALDI-TOF mass spectrometry. Genome Res 1997 7 378-388. 

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