What causes fragmentation in mass spectrometry?
Fragmentation occurs when energetically unstable molecular atoms dissociate (either through homolytic or heterolytic cleavage) as they pass through the ionization chamber of a mass spectrometer.
What is EI chemistry?
Electron ionization (EI, formerly known as electron impact ionization and electron bombardment ionization) is an ionization method in which energetic electrons interact with solid or gas phase atoms or molecules to produce ions. EI is the most useful for organic compounds which have a molecular weight below 600.
Is ionization a type of chemical reaction?
When salt is dissociated, its constituent ions are simply surrounded by water molecules and their effects are visible (e.g. the solution becomes electrolytic). However, no transfer or displacement of electrons occurs. Actually, the chemical synthesis of salt involves ionization. This is a chemical reaction.
When an electron is ionized it quizlet?
Ionization is the process by which ions are formed by gain or loss of an electron from an atom or molecule. If an atom or molecule gains an electron, it becomes negatively charged (an anion), and if it loses an electron, it becomes positively charged (a cation).
How does electron impact ionization lead to fragmentation?
Electron impact ionization yields molecular radical ions, also called odd electron ions. Their fragmentation is very common and is often predicted through an understanding of free radical chemistry. Chemical ionization yields even electron ions that are less prone to fragmentation.
Why do we need to know about fragmentation mechanisms?
Cleavage of M + (also written M +.) ions from electron impact ionization or [M +1] + ions from chemical ionization at bonds near the site of ionization gives smaller fragment ions. The appearance of fragment ions in the mass spectrum and an understanding of fragmentation mechanisms can provide information about the structure of unknown compounds.
How is chemical ionization used in mass spectrometry?
Chemical ionization (CI) is a soft ionization technique used in mass spectrometry. CI is based on the reactions of gaseous analyte molecules with an excess of ions formed by electron bombardment of a reagent gas. This was first introduced by Burnaby Munson and Frank H. Field in 1966.
How is fragmentation predicted in a cation chemistry?
The fragmentation that does occur is often predicted through an understanding of cation chemistry. A general rule is that the most favored fragmentation pathway cleaves the weakest bond or bonds near the site of ionization to give the most stable cation and/or radical products.
