Collision-induced ionization

Characteristic trends in the fragmentation patterns of 1,4-benzodiazepines can be observed using ion-trap mass spectrometry (MS). For the l,4-benzodiazepin-2-one 15, ion fragmentation was largely dictated by the attached substituents, R1, Rz, R3, and R4 <2000RCM2061>. Using collision-induced ionization (CID) spectrometry, the C-3-unsubstituted analogues were shown to eliminate CO while the hydroxylated compounds predominantly... 

The kinetic energies of the vaporized species were evaluated by simple calculations, performed on the basis of the experimental setup They are in the 1-10-meV range, at least three order of magnitude less than those necessary to promote effective gas-phase collision-induced ionization and decomposition processes and, consequently, collisional phenomena cannot be held responsible for ion production. 

There are two important distinctions between the quasi-molecular ion and a molecular ion formed by conventional electron. First, the energy imparted to the sample molecule during the collision-induced ionization is relatively low (<20 eV for methane as the reactant gas). Second, the quasi-molecular ion is an even-electron species and therefore more stable than the odd-electron molecular ion. Quasi-molecular ions are therefore almost always seen in Cl mass spectra. 

Time-of-flight mass spectrometers have been used as detectors in a wider variety of experiments tlian any other mass spectrometer. This is especially true of spectroscopic applications, many of which are discussed in this encyclopedia. Unlike the other instruments described in this chapter, the TOP mass spectrometer is usually used for one purpose, to acquire the mass spectrum of a compound. They caimot generally be used for the kinds of ion-molecule chemistry discussed in this chapter, or structural characterization experiments such as collision-induced dissociation. Plowever, they are easily used as detectors for spectroscopic applications such as multi-photoionization (for the spectroscopy of molecular excited states) [38], zero kinetic energy electron spectroscopy [39] (ZEKE, for the precise measurement of ionization energies) and comcidence measurements (such as photoelectron-photoion coincidence spectroscopy [40] for the measurement of ion fragmentation breakdown diagrams). 

Fragmentor voltage Over 220 V Under 90 V 110-150V Collision-induced dissociation effect Poor ionization efficiency Good ionization efficiency... 

By CH4-chemical ionization two predominant ions from DDS were formed in the ion source m/z 163 (M + 1) and m/z 165 (M + 3), which were accelerated and separated in the first quadrupole. Decomposition by collision activation with argon then occurred in the second quadrupole and the resulting daughter ions were separated in the third quadrupole to give rise to collision-induced spectra (equations 41-43). When carrying out the analysis with a solid inlet MS-MS system (TSQ) it was observed that, when operating TSQ in the multiple ion detection mode and selecting the ions m/z 63, 83, 85,99 and 101, only in the third quadrupole was there no interference from other m/z 163 and 165 precursor ions . ... 

The apparatus and techniques of ion cyclotron resonance spectroscopy have been described in detail elsewhere. Ions are formed, either by electron impact from a volatile precursor, or by laser evaporation and ionization of a solid metal target (14), and allowed to interact with neutral reactants. Freiser and co-workers have refined this experimental methodology with the use of elegant collision induced dissociation experiments for reactant preparation and the selective introduction of neutral reactants using pulsed gas valves (15). Irradiation of the ions with either lasers or conventional light sources during selected portions of the trapped ion cycle makes it possible to study ion photochemical processes... 

Substituted tetrazoles reacting in the mass spectrometer with acyl ions afforded 2,5-disubstituted 1,3,4-oxadiazoles with nitrogen loss. Tandem mass spectrometry allowed for the collision-induced dissociation of the products. Chemical ionization was the better method to make the transformation. A scheme for the transformation of 5-substituted tetrazoles into 2,5-disubstituted 1,3,4-oxadiazoles was proposed (Scheme 1) <2001JMP1069>. The fragmentation patterns of monocyclic l,3,4-oxadiazolium-2-thiolates have been proposed by Ollis and Ramsden <1974J(P1)645>. 

Cuyckens F, Shahat AA, Van den Heuvel H, Abdel-Shafeek KA, El-Messiry MM, Seif-El Nasr MM, Pieters L, Vlietinck AJ and Claeys M. 2003. The application of liquid chromatography-electrospray ionization mass spectrometry and collision-induced dissociation in the structural characterization of acylated flavonol O-glycosides from the seeds of Carrichtera annua. Eur J Mass Spectrom 9(4) 409-420. 

Guevremont, R., R.A. Yost, and W.D. Jamieson. 1987. Identification of PCB congeners by collision-induced dissociation of [M-C1+]- from oxygen-enhanced negative chemical ionization mass spectrometry. Biomed. Environ. Mass Spectrom. 14 435-441. 

CID collision-induced dissociation ESI electrospray ionization MS mass spectrometry... 

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... 

There have been fewer studies of the reactions of M ions with potential ligand molecules. Laser ablation, which has been the major ionization source for the production of bare metal ions, produces very few negative ions. Electron impact with low-energy electrons (12 eV) of metal carbonyls has been used to produce [Co(CO)4]- and Fc( CO)4 from Co2(CO)8 and Fe(CO)5. Collision-induced dissociation of these two anions produced Co- and Fc, which could be isolated. Both Co- and Fe were reacted with H2S, aliphatic thiols, aromatic thiols, CS2, and disulfides (153). Reactions with H2S gave the metal monosulfide anion [MS]-, which reacted with H2S by two pathways. 

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