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Fragmentation is a type of chemical dissociation, in which the removal of the electron from the molecule results in ionization. Removal of electrons from either sigma bond, pi bond or nonbonding orbitals causes the ionization. [2] This can take place by a process of homolytic cleavage or homolysis or heterolytic cleavage or heterolysis of the ...
The principal fragmentation modes are described as follows: Alpha-cleavage can occur on either side of the carbonyl functional group since an oxygen lone pair can stabilize the positive charge. Alpha cleavage of carbonyl compounds. β-cleavage is a characteristic mode of carbonyl compounds' fragmentation due to the resonance stabilization.
Generally this topic is discussed when covering tandem mass spectrometry fragmentation and occurs generally by the same mechanisms. [3] [4]For example, of a mechanism of alpha-cleavage, an electron is knocked off an atom (usually by electron collision) to form a radical cation.
Heterolytic fragmentation. Heterolytic fragmentation is bond cleavage where the bonding electrons remain with only one of the fragment species. [11] In CID, charge remote fragmentation is a type of covalent bond breaking that occurs in a gas phase ion in which the cleaved bond is not adjacent to the location of the charge.
The x-axis of a mass spectrum represents a relationship between the mass of a given ion and the number of elementary charges that it carries. This is written as the IUPAC standard m/z to denote the quantity formed by dividing the mass of an ion (in daltons) by the dalton unit and by its charge number (positive absolute value).
Electron-transfer dissociation (ETD) is a method of fragmenting multiply-charged gaseous macromolecules in a mass spectrometer between the stages of tandem mass spectrometry (MS/MS). [1] Similar to electron-capture dissociation, ETD induces fragmentation of large, multiply-charged cations by transferring electrons to them. [2]
Electron-capture dissociation was developed by Roman Zubarev and Neil Kelleher while in Fred McLafferty's lab at Cornell University.Irradiation of melittin 4+ ions and ubiquitin 10+ ions (trapped in FT-MS cell) by laser pulses not only resulted in peculiar c', z fragmentation but also charge reduction.
In chemistry, bond cleavage, or bond fission, is the splitting of chemical bonds. This can be generally referred to as dissociation when a molecule is cleaved into two or more fragments. [1] In general, there are two classifications for bond cleavage: homolytic and heterolytic, depending on the nature of the process