Resonant two-photon ionization for the identification of thermal decomposition products in the laser desorption of small peptides

Resonant two-photon ionization (R2PI) of nonaromatic peptides is studied with the use of CBZ-derivatization as a means of providing an absorbing aromatic center in the near-UV region at 266 nm. The peptides are then vaporized with a pulsed laser-induced desorption method, with subsequent entrainment of the desorbed neutral species into a supersonic expansion. The CBZ-derivatized peptides are then ionized and mass analyzed in a time-of-flight mass spectrometer. The resulting R2PI/MPI-induced fragmentation-ionization patterns generally yield the molecular ion as well as fragments due to specific bond cleavages which are characteristic of the structure of the peptide. Thus, the resulting mass spectra can be used for identification and structural analysis of these small peptides. Most significantly, the laser-induced fragmentation can be used to distinguish between isomeric peptides containing Ile, Leu, or Nle.

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Resonant two-photon ionization of small peptides using pulsed laser desorption in supersonic beam mass spectrometry

Analytical Chemistry ◽

10.1021/ac00134a017 ◽

1987 ◽

Vol 59 (7) ◽

pp. 1003-1006 ◽

Cited By ~ 56

Author(s):

Roger. Tembreull ◽

David M. Lubman

Keyword(s):

Mass Spectrometry ◽

Pulsed Laser ◽

Laser Desorption ◽

Small Peptides ◽

Two Photon ◽

Photon Ionization

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267. Biological Monitoring of Thermal Decomposition Products of a 4,4-Methylene Diphenyl Diisocyanate (MDI) and Toluenediisocyanate (TDI)Polyurethane (PUR)

10.3320/1.2764936 ◽

1999 ◽

Author(s):

G. Skarping ◽

M. Dalene ◽

P. Lind

Keyword(s):

Thermal Decomposition ◽

Biological Monitoring ◽

Decomposition Products ◽

Methylene Diphenyl Diisocyanate ◽

Thermal Decomposition Products

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Theoretical study on the formation of carbon disulfide and ammonia from thermal decomposition products of thiourea

Journal of Theoretical and Computational Chemistry ◽

10.1142/s0219633614500229 ◽

2014 ◽

Vol 13 (04) ◽

pp. 1450022 ◽

Cited By ~ 1

Author(s):

Zerong Daniel Wang ◽

Meagan Hysmith ◽

Perla Cristina Quintana

Keyword(s):

Thermal Decomposition ◽

Carbon Disulfide ◽

Density Functional ◽

Basis Sets ◽

Structural Isomer ◽

Consecutive Reaction ◽

Functional Theory ◽

Decomposition Products ◽

Thermal Decomposition Products ◽

Hybrid Module

The formation of carbon disulfide ( CS 2) and ammonia ( NH 3) from the thermal decomposition products of thiourea has been studied with MP2, and hybrid module-based density functional theory methods (B3LYP, MPW1PW91 and PBE1PBE), each in conjunction with five different basis sets (6-31+G(2d,2p), 6-311++G(2d,2p), DGDZVP, DGDZVP2 and DGTZVP). The free energy changes and activation energies for all the five primitive reactions involved in the formation of CS 2 and NH 3 have been compared and discussed. The results indicate that CS 2 is most likely formed in a consecutive reaction path that consists of the addition of hydrogen sulfide ( H 2 S ) to isothiocyanic acid (HNCS) to generate carbamodithioic acid and subsequent decomposition of carbamodithioic acid. By contrast, thiocyanic acid (HSCN) as the structural isomer of isothiocyanic acid is not likely the source of CS 2.

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