A new trisector tandem mass spectrometer for neutralization—reionization studies

doi:10.1016/0168-1176(92)87040-L

International Journal of Mass Spectrometry and Ion Processes

Volume 113, Issue 1, 15 February 1992, Pages 35-58

International Journa...

https://doi.org/10.1016/0168-1176(92)87040-L Get rights and content

Abstract

A new trisector EBE mass spectrometer is modified to accommodate neutralization—reionization mass spectrometry (NRMS) experiments. The instrument is equipped with dual collision cells and an electro-static deflector in the field-free region between B and E for the study of neutralization—reionization (NR) reactions. Combined with linked scanning, a third collision cell, situated after the ion source, can be used for the charge reversal of mass-selected cations (⁺NR⁻¹) or anions (⁻NR⁺). Collisionally-activated dissociation (CAD) processes can be studied in any one of the three cells. The capabilities of the instrument are illustrated with specific problems pertaining to gas phase chemistry and mass spectral analysis: combined NR and CAD experiments are used to investigate the structures and isomerization tendencies of C₂H₅O⁺ and C₄H₈O⁺ ions, and the stabilities and reactivities of the hypervalent radicals CH₂ = CHOH₂ and ClHCl and the Norrish-type II biradical CH₂CH₂CH₂CHOH. It is demonstrated that detection of the neutrals eliminated in unimolecular ion dissociations significantly facilitates differentiation of molecular isomers and elucidation of peptide ion fragmentation mechanisms.

References (43)

C. Wesdemiotis et al.
Chem. Rev.
(1987)
M.J. Bertrand et al.
Proc. 37th ASMS Conf. Mass Spectrometry and Allid Topics
(1989)
N. Heinrich et al.
J. Am. Chem. Soc.
(1988)
J.C. Traeger et al.
Int. J. Mass Spectrom. Ion Processes
(1986)
B.W. Williams et al.
J. Chem. Phys.
(1980)
S. Hammerum
Mass Spectrom. Rev.
(1988)
C. Wesdemiotis et al.
Org. Mass Spectrom.
(1988)
P.O. Danis et al.
J. Am. Chem. Soc.
(1983)
J.K. Terlouw et al.
Org. Mass Spectrom.
(1985)
J.K. Terlouw et al.
J.L. Holmes
Mass Spectrom. Rev.
(1989)

G.I. Gellene et al.

Acc. Chem. Res.

(1983)

P.O. Danis et al.

Anal. Chem.

(1986)

C.E.C.A. Hop et al.

Org. Mass Spectrom.

(1991)

F.W. McLafferty et al.

J. Am. Chem. Soc.

(1980)

P.C. Burgers et al.

Org. Mass Spectrom.

(1984)

P.O. Danis et al.

Anal. Chem.

(1986)

R. Feng et al.

J. Am. Chem. Soc.

(1987)

F.W. McLafferty et al.

Org. Mass Spectrom.

(1988)

F.W. McLafferty

Science

(1990)

R. Orlando et al.

Anal. Chem.

(1990)

R. Feng et al.

Int. J. Mass Spectrom. Ion Processes

(1988)

G.I. Gellene et al.

J. Phys. Chem.

(1984)

S.F. Selgren et al.

J. Chem. Phys.

(1988)

A.G. Harrison et al.

Int. J. Mass Spectrom. Ion Processes

(1986)

VG Analytical Limited, Wytheshawe, Machester, M23 9LE...

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A new trisector tandem mass spectrometer for neutralization—reionization studies

Abstract

Chem. Rev.

Proc. 37th ASMS Conf. Mass Spectrometry and Allid Topics

J. Am. Chem. Soc.

Int. J. Mass Spectrom. Ion Processes

J. Chem. Phys.

Mass Spectrom. Rev.

Org. Mass Spectrom.

J. Am. Chem. Soc.

Org. Mass Spectrom.

Mass Spectrom. Rev.

Acc. Chem. Res.

Anal. Chem.

Org. Mass Spectrom.

J. Am. Chem. Soc.

Org. Mass Spectrom.

Anal. Chem.

J. Am. Chem. Soc.

Org. Mass Spectrom.

Science

Anal. Chem.

Int. J. Mass Spectrom. Ion Processes

J. Phys. Chem.

J. Chem. Phys.

Int. J. Mass Spectrom. Ion Processes