Collisionally-activated dissociation

Collision-induced dissociation (or decomposition), abbreviated CID. An ion/neutral process wherein the (fast) projectile ion is dissociated as a result of interaction with a target neutral species. This is brought about by conversion during the collision of part of the translational energy of the ion to internal energy in the ion. The term collisional-activated dissociation (or decomposition), abbreviated CAD, is also used. 

Conventional wisdom concerning thermal unimolecular reactions would seem to dictate that this must then be a Lindemann-type collisionally activated dissociation reaction scheme such as is in Equation (17). Application of the steady-state... 

Cadmium thiocyanates, 17 333-336 Cadmium trifluoroacetates, 17 25, 26 CAD spectra, see Collisionally activated dissociation spectra... 

Collisionally activated dissociation occurs between capillary and skimmer... 

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. 

What is collisionally activated dissociation At what points in a mass spectrometer does it occur ... 

Mass spectrum of m/z 304 after collisionally activated dissociation... 

Figure for Problem 25-19 Left Mass spectrum of collisionally activated dissociation products from mlz 304 positive ion from atmospheric pressure chemical ionization mass spectrum of cocaine. Right Chromatogram obtained by selected reaction monitoring. [From G. Singh. V. Arora,... 

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. 

C H7 ions were generated by collisionally activated dissociation (CAD) in the gas phase from various precursors.216Mass spectrometric analysis showed thathomoallyl chloride and cyclopropylmethyl chloride generated primarily cation 521, whereas cyclobutyl chloride gave a substantial amount of bicyclobutonium ion 522. 

The cyanodiazonium ion NCN2+ proposed as a transient intermediate in solution,503 has been observed in the gas phase by Cacace et al.504 It was generated by ionization of NF3 and cyanamide and characterized by collisionally activated dissociation. The linear structure of C, , v symmetry (216) has been found442 to be the global minimum by high-level ab initio calculations [MP2(FU)/6-31G ]. Of the protonated structures the dication protonated on the cyano nitrogen is 55.0 kcal mol 1 more stable. 

B. M. Warrack, M. E. Hail, A. Triolo, F. Animati, R. Seraglia, and P. Traldi, Observation of internal monosaccharide losses in the collisionally activated dissociation mass spectra of anthra-cycline aminodisaccharides, J. Am. Soc. Mass Spectrom., 9 (1998) 710-715. 

In the studies outlined below, collisionally activated dissociation (MS/MS) experiments were attempted as a means of helping establish the identities of a number of anions. In every case tried, however, the parent anions appeared to undergo electron detachment with no daughter ion production observed. 

McLafferty et al. (37) studied the collisionally activated dissociation (CAD) of the ions resulting from the fast-atom bombardment ionization of cyano- and methylcobalamins, using a tandem mass spectrometer. They showed that mlz 1329 is produced only from the quasi-molecular ion. Similar CAD spectra are produced by both the quasi-molecular ions and the 1329 peak, indicating that essentially all fragmentation arises from this latter ion. CAD spectra produced for the 1329 ion derived from methylcobalamin or vitamin B12 coenzyme are also similar. This is consistent with the work of Taylor (10), who used linked-scan metastable ion techniques in a conventional double-focusing mass spectrometer to show the same thing. The sequential... 

Hsu, F.-F., and Turk, 1 1999. Structural Characterization of triacylglycerols as lithiated adducts by electrospray ionization mass spectrometry using low-energy collisionally activated dissociation on a triple stage quadrupole instrument. J. Am. Soc. Mass Spectrom., 10, 587-599. 

The basic NR mass spectrum contains information on the fraction of undissociated (survivor) ions and also allows one to identify dissociation products that are formed by purely unimolecular reactions. NRMS thus provides information on the intrinsic properties of isolated transient molecules that are not affected by interactions with solvent, matrix, surfaces, trace impurities, radical quenchers, etc. However, because collisional ionization is accompanied by ion excitation and dissociation, the products of neutral and post-reionization dissociations overlap in the NR mass spectra. Several methods have been developed to distinguish neutral and ion dissociations and to characterize further short lived neutral intermediates in the fast beam. Moreover, collisionally activated dissociation (CAD) spectra have been used to characterize the ions produced by collisional reionization of transient neutral intermediates [51]. This NR-CAD analysis adds another dimension to the characterization of neutral intermediates, because it allows one to uncover isomerizations that do not result in a change of mass and thus are not apparent from NR mass spectra alone. 

C. Zhao, B. Xie, S.-Y. Chan, C. E. Costello, and P. B. O Connor, Collisionally activated dissociation and electron capture dissociation provide complementary structural information for branched per-methylated oligosaccharides,./. Am. Soc. Mass Spectrom., 19 (2008) 138-150. 

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