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Reflector TOF

In a reflector TOF instrument, PSD can be performed. The Qq-TOF is an oa-TOF with a quadrupole as a precursor selector. TOF-TOF is a type of instrument that has emerged in recent years and has enabled MALDI-TOF instruments that can deliver good MS/MS data. There are also examples of instruments with two consecutive reflector TOFs. TOF analyzers can also be coupled to ion traps and to sector instruments. See Chapter 3 for more thorough MS/MS descriptions. [Pg.45]

The reflector or reflectron has been developed by Mamyrin. [35] In the reflector TOF analyzer - often abbreviated ReTOF - the reflector acts as an ion mirror that focuses ions of different kinetic energies in time. Its performance is improved by using two-stage or even multistage reflector designs. [Pg.119]

Because not all the molecules get desorbed at the same time in exactly the same place, slightly different velocities are obtained for identical ions which can result in a broad peak and poor resolution. Using a reflector TOF set-up (Fig. 4.4) instead of the linear set-up shown above (Fig. 4.3), can overcome this problem. [Pg.91]

For the MALDI-MS analysis of intact proteins, FI CCA (alpha-cyano-4-hydroxycinnamic acid), SA (sinapinic acid) or DHB (2,5-dihydroxybenzoic acid) matrices and the dried-droplet deposition method for sample preparation are typically used [13, 14] (Table 3.1). Depending on the properties of the protein, it is often necessary to test a series of solvents and matrices to optimize the outcome of the MALDI-MS experiment. Peptides and small proteins below molecular weight 20000 Da are often amenable to analysis using HCCA matrix and reflector TOF-MS mode, whereas larger proteins may produce better results with SA or DHB matrix in the linear TOF-MS mode. Hydrophobic proteins can be analyzed using the HCCA matrix dissolved in high concentrations of formic acid (up to 30%) [15]. When using cirmamic acid matrices, SA and HCCA, and the... [Pg.109]

TOF mode and reflector TOF mode for the observation of labile modifications [45] (differences between linear and reflectron TOFs in the detection of metastable ions are detailed in Chapter 2). It may also be useful to try negative- and positive-ion modes, as certain species ionize more efficiently in the negative-ion mode [46]. An alternative to the MALDl-MS/MS analysis of modified peptides is electron-transfer dissociation (ETD)-based ESl-MS/MS, where the modification is retained during peptide ion fragmentation, making the assignment of the modification site more straightforward. [Pg.118]

The spectra of heptane solubles discussed so far were in linear TOF mode. The heptane soluble fraction was also examined in reflector TOF mode, and the spectrum shown in Figure 33.3B is at a LP of 40% of the maximum. The low mass limit was at m/z 200, the maximum intensity was at m/z 300, and the upper mass limit lay between... [Pg.736]

Fig. 6.9 Schematic view of the lA-TOF system. Gas-phase sample molecules are ionized by alkali metal ion attachment and become adduct ions in the lA ion source. The adduct ions are extracted through the aperture into the differential pumping region, pass through the skimmer, and are introduced into the TOF mass spectrometer. Because 100 Pa of gas is introduced into the lA ion source, a differential pumping system is used to evacuate the gas since the TOF mass spectrometer must be kept in a high vacuum condition. The orthogonal acceleration reflector TOF mass spectrometer realizes mass spectrometry with a high mass resolution over a wide mass range. (Reprinted with permission from Ref [88]. 2007, John Wiley and Sons)... Fig. 6.9 Schematic view of the lA-TOF system. Gas-phase sample molecules are ionized by alkali metal ion attachment and become adduct ions in the lA ion source. The adduct ions are extracted through the aperture into the differential pumping region, pass through the skimmer, and are introduced into the TOF mass spectrometer. Because 100 Pa of gas is introduced into the lA ion source, a differential pumping system is used to evacuate the gas since the TOF mass spectrometer must be kept in a high vacuum condition. The orthogonal acceleration reflector TOF mass spectrometer realizes mass spectrometry with a high mass resolution over a wide mass range. (Reprinted with permission from Ref [88]. 2007, John Wiley and Sons)...
Fig. 4.12. An orthogonal acceleration reflector TOF instrument. See text for discussion. Reproduced from Ref. [49] by permission. John Wiley Sons, 2000. Fig. 4.12. An orthogonal acceleration reflector TOF instrument. See text for discussion. Reproduced from Ref. [49] by permission. John Wiley Sons, 2000.
The 2 pi of the concentrated peptide solution was mixed with 4 pi of 2,5-dihydroxybenzoic acid [ 7 mg in 500 pi of the mixture of acetonitrile/0.1% trifluoroacetic acid, 1/2 (v/v)]. The resulting mixture was applied to the MALDI steel plate and left to crystallise. Afterwards, the MALDI-TOF mass spectra were measured by a BIFLEX IV instrument (Bruker, Germany) under appropriate conditions (potential 19 kV on the plate and 15.05 kV on the deflector, positive reflector mode potential 20 kV, laser intensity 50 or 60%). The range of detected masses was from 600 to 3000 Da. For the external calibration the standard mixture of peptides M-Pep was used. [Pg.175]

Instruments are calibrated with substances of known relative molecular mass and very accurate mass measurements can be made with this type of analyser. Sensitivity is very high and there is virtually no upper limit to the working mass range. The performance of TOF instruments can be improved further by the incorporation of an electrostatic reflector (reflectron) which ensures that all ions of identical mass reach the detector simultaneously by correcting for any differences in their kinetic energies. [Pg.430]

Figure 2.10. Schematic of a MALDI-TOF mass spectrometer with reflector and time-lag focusing. Reprinted from A. Westman-Brinkmalm and G. Brinkmalm (2002). In Mass Spectrometry and Hyphenated Techniques in Neuropeptide Research, J. Silberring and R. Ekman (eds.) New York John Wiley Sons, 47-105. With permission of John Wiley Sons, Inc. Figure 2.10. Schematic of a MALDI-TOF mass spectrometer with reflector and time-lag focusing. Reprinted from A. Westman-Brinkmalm and G. Brinkmalm (2002). In Mass Spectrometry and Hyphenated Techniques in Neuropeptide Research, J. Silberring and R. Ekman (eds.) New York John Wiley Sons, 47-105. With permission of John Wiley Sons, Inc.
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). [Pg.41]

The mass accuracy is highly dependent on the mode the instrument is operating in. In the reflector mode, with time-lag focusing, the best MALDI-TOF and oa-TOF instruments are capable of achieving <5 ppm with internal standards, provided that the isotopes are resolved. In many cases it is not possible to add internal calibrants, and then the error in mass accuracy is often increased to 50-100 ppm. Operation of an instalment in a linear mode will typically decrease the mass accuracy. [Pg.44]

Fig. 4.7. The molecular ion signal of Ceo at m/z 720 (a) and the quasimolecular ion signal of bovine insulin, m/z 5734.6, (b) as obtained on a TOF instrument in linear mode (left) and reflector mode (right). All other experimental parameters remained unchanged. Fig. 4.7. The molecular ion signal of Ceo at m/z 720 (a) and the quasimolecular ion signal of bovine insulin, m/z 5734.6, (b) as obtained on a TOF instrument in linear mode (left) and reflector mode (right). All other experimental parameters remained unchanged.
Example Regardless of the manufacturer of the hardware, the effect of a time lag on resolution is quite dramatic. The resolving power of linear instruments is improved by a factor of 3-4 and reflector instruments become better by a factor of about 2-3. [36] The advantages are obvious by comparison of the molecular ion signal of Ceo as obtained from a ReTOF instrument with continuous extraction (Fig. 4.7) and from the same instrument after upgrading with PIE (Fig. 4.12), or by examination of MALDI-TOF spectra of substance P, a low mass peptide, as obtained in continuous extraction mode and after PIE upgrade of the same instrument (Eig. 4.11). [Pg.124]

Fig. 4.56. Schematic of the Q-TOF Ultima with ESI ion source in MS/MS mode. The TOF analyzer has a double reflector for higher resolution. Courtesy of Waters Corporation, MS Technologies, Manchester, UK. Fig. 4.56. Schematic of the Q-TOF Ultima with ESI ion source in MS/MS mode. The TOF analyzer has a double reflector for higher resolution. Courtesy of Waters Corporation, MS Technologies, Manchester, UK.
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. [Pg.87]

Fig. 17.7. The MALDI schematic design of a MALDI ToF instrument (Micromass ToF Spec 2E, MMUK) showing ion generation via laser desorption (UV/IR), followed by ion acceleration through the field-free ToF-mass analyser, where the ions are reversed as they enter the reflector to end at the detectors. Fig. 17.7. The MALDI schematic design of a MALDI ToF instrument (Micromass ToF Spec 2E, MMUK) showing ion generation via laser desorption (UV/IR), followed by ion acceleration through the field-free ToF-mass analyser, where the ions are reversed as they enter the reflector to end at the detectors.
MALDI-TOF-MS may be operated in either linear or reflector mode. Due to the cationic character of the peptides investigated, detection is performed in a positive mode. [Pg.15]


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