Curved-field reflectron

Example The curved-field reflectron of a coaxial ReTOF instrument occupies a large portion (D) of the total flight path s = li + D) and uses 86 lens elements whose voltages are set by 85 precision potentiometers located between them [47], The distance f between ion source and reflector entrance provides sufficient field-free flight path for metastable dissociations. 

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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... 

Warscheid, B. Fenselau, C. Characterization of Bacillus spores species and their mixtures using possource decay with a curved-field reflectron. Anal. Chem. 2003, 75, 5618-5627. 

R. J. Cotter, W. Griffith, and C. Jelinek. Tandem Time-of-Flight (TOF/TOF) Mass Spectrometry and the Curved-Field Reflectron. J. Chromatogr., B855(2007) 2-13. 

T. J. Cornish and R. J. Cotter. A Curved-Field Reflectron for Improved Energy Focusing of Product Ions in Time-of-Flight Mass Spectrometry. Rapid Commun. Mass Spectrom., 7(1993) 1037-1040. 

Example The curved-field reflectron of a coaxial ReTOF instrument occupies a large portion D) of the total flight path s = li + D) and uses 86 lens elements... 

Fig. 4.8. Coaxial curved-field reflectron TOF spectrometer. The total length is about 1 m. Adapted from Ref. [37] with permission. John WUey Sons, 1995.

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. 

Trajectories for CID fragmentation of ions of 500 Th. The focal points in energy of the product ions of 400 and 300 Th are indicated for a linear field reflectron and for a curved field reflectron. Reproduced (modified) from Cotter R.J., Time-Of-Flight Mass Spectrometry Instrumentation and Applications in Biological Research, ACS, Washington, DC, 1997, with permission. 

Complete characterization for each ionization event can be obtained by the curved-field reflectron that, in addition to greatly enhancing signal-to-noise levels from multiple acquisition, provides the means to rapidly acquire product- and metastable-ion spectra. ... 

Figure 4.8. Schematic of a TOF/TOF tandem instrument with a curved field reflectron as the MS-2. The mass-selection ion gate is located at the focal plane of MS-1. The MS-1 region also contains a collision cell. (Reproduced from ref. 45 by permission of the American Chemical Society, Washington, DC, copyright 2004.)...

Cordero MM, Cornish TJ, Cotter RJ, and Lys lA (1995) Sequencing peptides without scanning the reflectron post-source decay with a curved-field reflectron time-of-flight mass spectrometer. Rapid Communications in Mass Spectrometry 9 1356-1361. 

The concept of the TOF mass analyzer was first proposed by Stephens in 1946 [3], and the first instrument was demonstrated by Cameron and Eggers in 1948 [4]. Since then, several important advances in TOF technology have occurred, including time-lag focusing and two-stage acceleration techniques demonstrated by Wily and McLaren in 1955 [5], reflec-tron configuration demonstrated by Mamyrin et al. in 1973 [6], and curved-field reflectron demonstrated by Cornish and Cotter in 1993 [7]. 

Ilchenko S, Cotter RJ. Collision energetics in a tandem time-of-flight (TOF/TOF) mass spectrometer with a curved-field reflectron. Int J Mass Spec 2007 265(2—3) 372—81. 

Mass calibration is relatively straightforward even though it does not follow a simple linear or square-root mass law. Figure 8.24 shows the product-ion mass spectrum obtained on the curved-field reflectron TOF for the synthetic peptide... 

FIGURE 8.20 Schematic representation of the method used to determine the voitages on the retarding ring eiectrodes of a curved-field reflectron. The voltages placed on the reflectron lenses are determined from the equation of a circle = + x where V is a voltage, x is distance, and... 

FIGURE 8.21 Coaxial, curved-field reflectron TOP with gate and pulsed valve shown. (Reprinted with permission from reference 15). 

FIGURE 8.22 Mass spectra obtained for the peptide dermenkephalin using a curved-field reflectron. (a) Ion gate OFF. (b) Ion gate ON. (Reprinted with permission from reference 14). 

FIGURE 8.27 Comparison of the voltages in time-of-flight mass spectrometers using (a) a single-stage reflectron, (b) a dual-stage reflectron, (c) the curved-field reflectron, and (d) a quadratic reflectron. 

In a more recent version of their tandem instrument (Figure 9.11), Cornish and Cotter used a curved-field reflectron in the second mass analyzer. In this instrument the mass spectrum of caffeic acid, obtained by passing the ions through both reflectrons, revealed an extraordinary mass resolution of 1 part in 13,500 (Figure 9.12). In addition, the mass spectra in Figure 9.13 illustrate the fact that unit mass resolution... 

FIGURE 9.12 Molecular-ion region of the mass spectrum of cafleic acid, obtained on a tandem (RTOF-RTOF) time-of-flight mass spectrometer with a curved-field reflectron. 

An alternative approach proposed by Musselman et al. utilizes a curved-field reflectron TOF analyzer as MS2. In their scheme, MSI would be scanned (when continuous ionization is used), while the curved-field reflectron TOF samples the... 

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