Collisional activation mass spectrometry

The SiCITt+ (x = 1-3) (41-43) cations have been generated upon electron ionization (El) of H3SiCH2Cl155. Collisional activation mass spectrometry (CA-MS) confirms that the hydrogen atoms reside on the carbon atom rather than on silicon in these ions — findings which are in keeping with the results from ab initio calculations156. 

An intriguing application of this hypothesis may have been observed in the mass spectrometric behavior of MTO.86 Loss of H2 and CO from the parent ion were the major processes observed in both metastable ion and collisional activation mass spectrometry. Both were viewed as unusual the latter, in particular, required a rationale for forming a C—O bond. The authors proposed migration of carbon to oxygen in the parent ion to form a methoxyrhenium complex of the same mass, followed by sequential back migration of the hydrogens ... 

Organophosphorus Chemistry series regularly lists new mass spectra in the Physical Methods chapter . With this in mind, an approach which considers fundamental aspects of organophosphorus ions (i.e. structure and reactivity) in the gas phase has been adopted. The gas-phase structure and reactivity of ions can be probed via several different techniques, including thermochemical measurements, kinetic energy release of metastable ions, collisional activation mass spectrometry, neutralization reionization mass spectrometry and ion-molecule reactions. An example is the molecule HCP (Table 1) its ionization potentiaP, proton affinity and the IR and rotational spectroscopy of the HCP ion " have all been determined in the gas phase. Another important tool for understanding the structure and reactivity of gas phase ions is ab initio molecular orbital theory. With advances in computational hardware and software, it is now possible to carry out high-level ab initio calculations on smaller systems. Indeed, the interplay between experiment and theory has fuelled many studies ... 

Multiple excitation collisional activation Mass spectrometry... 

Levsen, K. Schwarz, H. Collisional Activation Mass Spectrometry - A New Probe for Structure Determination of Ions in the Gaseous Phase. Angew. Chem. 1976, 88, 589-601. 

Shukla, A.K. and Futrell, J.H. (2000) Tandem mass spectrometry dissociation of ions by collisional activation./. Mass Spectrom., 35, 1069. 

Collisional activation (CA) spectrometry is another valuable tool for the structural identification of gaseous ions30. Collisional activation produces a fragmentation pattern of long-lived ions in much the same way as conventional mass spectrometry yields fragments of the short-lived ions decomposing in the ion source. CA spectra are particularly well suited for the comparison of ions from different precursors. 

Mass Spectrometry.—It has been revealed by collisional activation mass spectral... 

Over the past years a number of small silicon-containing ions have been structurally characterized by collisional-activation mass spectrometiy. These ions have been used as precursors for the generation of their neutral counterparts via Neutralization-Reionization Mass Spectrometry (NRMS) . To a large extent the interest in small elusive silicon-containing molecules is due to the role which these species have been postulated to play as intermediates and building blocks in the genesis of interstellar matter" . In particular, the different conceivable pathways which lead from atomic silicon cations to the formation of neutral silicon-containing molecules have been studied intensely" A second... 

An insight into the equilibria present in solutions of several complexes of the type (R3P)2HgX2 (X = C104, CF3COO) is provided by electrospray mass spectrometry (ES MS) (cf. Section 6.9.2.1.8). 39 In all cases the principal ions [(R3P)2HgX]+ are observed, even if these ions and other ionic constituents of the equilibria are known to be labile on the NMR timescale. In the presence of excess R3P the principal ions [(R3P)3HgX]+ appear. Also fragments of collisionally activated decomposition (CAD, can be influenced and controlled to some extent) are detected, e.g., [(R3P)HgX]+. 

The major fragmentation in mass spectra of 1,2,5-oxadiazoles is attributed to the loss of nitrile and nitrile oxide or expulsion of NO. The conversion of 3,4-dicyano-l,2,5-oxadiazole-2-oxide (3,4-dicyanofuroxan) 10 to cyanogen iV-oxide 11 (Equation 5) was investigated under the conditions of collisional activation (CA) and neutralization-reionization (NR) mass spectrometry. Flash vacuum thermolysis mass-spectrometry (FVT-MS) and flash vacuum thermolysis infra-red (FVT-IR) investigations of furoxans 10, 12, and 13 reveal that small amounts of cyano isocyanate accompany the formation of the main thermolysis product 11 <2000J(P2)473>. 

Online coupling of flash-vacuum pyrolysis and mass spectrometry was applied to 3,4-dicyano-l,2,5-oxadiazole-2-oxide (dicyanofuroxan). The 1,2,5-oxadiazole is almost quantitatively pyrolyzed at 500-600 °C. Using collisional activation, the main pyrolysis products were identified as NCCNO and (CN)2 <1997BSB545>. 

Most nitrile oxides are unstable, some of them are explosive. This fact hinders the study of their physical properties. Nevertheless, there are a number of publications concerning not only stable but also unstable nitrile oxides. In particular, mass spectral data for nitrile oxides among other unstable compounds containing an N+-X bond are summarized in a review (9). In such studies, the molecular ions must be generated using indirect procedures, including dissociative electron ionization, online flash-vacuum pyrolysis mass spectrometry, or ion-molecular reactions. Their characterization is mainly based on collisional activation and ion-molecular reactions. 

Morris H.R., Paxton T., Dell A., Langhome J., Berg M., Bordoli R.S., Hoyes J., and Bateman R.H. (1996), High sensitivity collisionally-activated decomposition tandem mass spectrometry on a novel quadrupole/orthogonal-acceleration time-of-flight mass spectrometer, Rapid Commun. Mass Spectrom. 10, 889-896. 

ShuMa, A.K. Fntrell, J.H. Tandem Mass Spectrometry Dissociation of Ions by Collisional Activation. J. Mass Spectrom. 2000,35,1069-1090. 

A number of methods have been described for determination of tetracycline (chlortetracycline, tetracycline, and oxytetracycline) residues in tissues of food-producing animals (53-62), fish (63), eggs (64), and honey (65,66). Most of these methods use reversed-phase HPLC for determination. However, one uses TLC with UV densitometry ( ) and one uses GLC ( ), and one uses a direct mass spectrometric method CAD MIKE spectrometry (collisionally activated decomposition mass-analyzed ion kinetic spectrometry) for oxytetracycline in milk and meat (62). Several use solid-phase extraction in the cleanup procedure using XAD-2 resin (56,58) or Cj g cartridges... 

In situ generation and characterization of [C,N2,S] ions (miz 72), formed by dissociative ionization of ionized [l,2,5]thiadiazolo[3,4-f][l,2,5]thiadiazole I , 79, has been made possible for the first time following collisional activation (CA) and neutralization-reionization (NR) mass spectrometry <1997JST(418)209>. 

Selected reaction monitoring is one of several techniques carried out by consecutive mass filters. These techniques are collectively called tandem mass spectrometry or mass spectrometry/mass spectrometry or simply MS/MS. The process In Q2 is collisionally activated dissociation. 

Tandem mass spectrometry has been particularly effective in molecular struclure dctemiinaiiiins. To increase the number and absolute abundance of peaks in the secondary mass spectrum, it is necessary lit add energy to the separated primary ions. Collisionally activated dissociation tCAD) is frequently used. 

The cyclopropylmethyl cation has recently been generated in the gas phase from both homoallyl chloride and cyclopropylmethyl chloride and studied using collisional activated dissociation mass spectrometry.216 Interestingly, cyclobutyl chloride, which yields the cyclopropylmethyl cation in the condensed phase, gives a substantial amount of the bicyclobutonium ion in the gas phase. 

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