An instrument hat analyzes ions according to their m/z ratio and measures electrically the number (abundance) of the ion.
2. Mass spectrum
A spectrum obtained when ions (usually n a beam) are separated according to the mass-to-charge (m/z) ratios of the ionic species present. It’s plot a graphical representation of m/z versus measured abundance information.
3. Fragmentation
The process to broke up a big molecules into fragments. The molecular ions are energetically unstable, and some of them will break up into smaller pieces. The more stable an ion is the more likely it is to form. The simplest case is that a molecular ion breaks into two parts - one of which is another positive ion, and the other is an uncharged free radical.
4. Ionization
The process to change a molecules into an ion by bombard it with a high-energy beam of electron. Collisions between indicate electron with the samples will make the samples loss one electron and form into an ion.
5. Electron ionsation
Ionisation of the sample by a beam of electro most often accelerated by a potensial of about 70 eV.
6. Chemical ionisation
Production of an ion through reaction of the sample molecule with another molecule that was excited beforehand
M + A+ MA+ + e-7. Ionization chamber
The place where the ionization take place.
8. Ion saparation
The ion that go out from the ionization chamber will be isolated base on their mass-to-charge ratio.
9. Deflection
Turning aside the ion or charged particles use magnetic field/electromagnet. For mass-to-charge ratio will be deflected in different value.
10.Detection
Monitoring the charged particles and measure the relative abundance for each ion based on their mass-to-charge ratio. Only the positive ion that will be detected and the neutral particles or radical one will be disappear by vacum pump.
11.Bombards
Attacking the molecule with a high-energy of electron beam.
12.Electon beam
A ray of light that contain a lot of electron.
13.Molecular ion (M+)
The molecule that have been bombard with the electron beam and become an ion. An ion formed by the removal (positive ion) or addition (negative ion) of one or more electron from a molecule without fragmentation of the molecular structure. It represents the commonest fragment ion to be formed - either because there are several ways in which it could be produced during fragmentation of the parent ion, or because it is a particularly stable ion.
14.Parent ion
An electrically charge molecular moiety that may dissosiate to form fragment, of which one or more may be electrically charge and one or more are neutral species. It can be a molecular ion or an electrically charge fragment of a molecular ion.
15.Radical ion (M+•)
An ion containing an unpaired electron that is thus both an ion and a free radical. The presence of the ood electron is denoted by placing a dot alongside the symbole for the charge.
16.Stable ion
Ion that is not sufficiently excited to dissociate into a daughter ion and associated neutral fragments or to react further in the tme frame of the mass spectrometric analisys under stated experimental conditions.
17.Peak
A localized region of a visible ion signal n mass spectrum. Although peaks are often associated with particular ion, the terms peak and on should not be used interchangeably.
18.Peak intensity
The height or area of a peak in a mas spectrum.
19.Relative intensity
Ratio of the peak ntensity to that of the base peak.
20.Relative abundance
Normalization to the base peak.
21.Base peak
The peak that appear in the mass spectrum corresponding to the m/z that has the greatest intensity. Ussualy, it show the most stable fragment that formed.
22.Molecular ion peak
The peak that appear in the rightest of spectrum. It show the mollecullar ion that formed and ussually show the mollecullar weight.
23.Nitrogen rules
The rules that helps us to identify nitrogen in a compound. If a conpound has
a) Zero or an even number of nitrogen atoms, its molecular ion willn have an even m/z value
b) An odd number of nitrogen atoms, its molecular ion will have an odd m/z value
24.Isotopic peak
Peak due to other isotope of the same chemical but different isotopic composition.
25.Mc Lafferty rearrangement
The rearrangement of cyclic compound that happend in Cγ. It is define as β-cleavage with concomitant specific transfer of a γ-hydrogen atom in a six member transition state in mono-unsaturated system.
26.α-cleavage
The cleavage of the compound into fragments in the position of Cα (the first atom carbon after the atom carbon which bonding with the group fuction). It’s ussually happened on ethers, aldehydes. ketons, esthers, carboxylic acid and amines.
27.β-cleavage
The cleavage of the compound into fragments in the position of Cβ (the second atom carbon after the atom carbon which bonding with the group fuction). It’s ussually happened on amines.
28.Diels-Alder reaction
The characteristic fragmentation pattern that happened on the cycloalkenes compound.
29.Isotope
The same atoms that have the different of the relative atomic mass.
30.Relative atomic mass
The weighted average of the masses of the isotopes on a scale on which a carbon-12 atom has a mass of exactly 12 units
31.Atomic mass
The mass scale is a relative one based upon an agreed definition of the mass of an elemental isotope standard.
32.Atomic weight
A commonly used term for average atomic weight of an element, calculated from the average of the constituent stable isotope masses of that element using the unified mass scale.
33.Assosiation ionisation
A cooperative ionisation process in which two excited atoms or molecules react together to form a single adduct ion and an electron.
34.Chemical ionisation (CI)
One type of ionization by the addition of charged species to a neutral molecule or by removal of a proton. The product ion is an even-electron ion with low internal energy and undergoes little fragmentation. The initial reaction can take place in vacuum in an electron-impact (EI) source containing relatively high pressures of gases such as ammonia or methane, or in an APCI source where the reactant ions are provided by a plasma created by corona discharge. The figure shows a Chemical Ionisation (CI) source insert.
35.Autoionisation
The spontaneous loss of an electron from a neutral species via a radiationless transition from a discrete electronic level to an ionized continuum level of the same energy.
36.Mass-to-charge ratio (m/z)
m/z is an axis in mass spectrum, represents relationship between the mass of a given ion and the number of elementary charges that it carries.
37.Alpha bond
In discussing the fragmentation mechanism of an ion, the bond adjacent to the site of ionisation is frequently referred to as an alpha bond.
38.Bond dissociation energy
Also referred as bond energy, it is the enthalphy change in breaking a single bond in a neutral molecule. Bond energies in ionized molecules can differ from those in uncharged species.
39.Metastable ion peak
Metastable ion peaks are usually broad peaks, and they frequently appear at non integral values of m/e.
40.Abundance
This term is used to describe the relative occurence of an ion. A mass spectrum is a plot of the ion abundances against the m/z values determined and is normalized to the most abundant ion. This term should be distinguished from the signal of the individual ion peak detected, is not used in spectra.
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