1. 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.
2. Acceleration
The process to make an ion or only charged particles become faster.
3. 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.
4. Association ionisation
A cooperative ionisation process in which two axcited atoms or molecules react together to form a single adduct ion and an electron.
5. Atomic mass
The mass of an atom. The mass scale is a relative one based upon an agreed definition of the mass of an elemental isotope standard.
6. 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.
7. 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.
8. Base peak
The tallest peak in the mass spectrum, that indicate the most abundant ion formed (peak of most stabilized fragment).
9. Bombards
Attacking the molecule with a high-energy of electron beam.
10. 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.
11. 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.
12. Deflection
Turning aside the ion or charged particles use magnetic/electric field.
13. Electon beam
A ray of light that contain a lot of electron.
14. Electron ionization
Ionization of the sample by a beam of electro most often accelerated by a potensial of about 70 eV.
15. Fragment
The product of fragmentation process in MS.
16. Fragmentation
A cleavage bond process, usually form a fragment. The most stable fragment has the highest spectrum peak in mass spectrum.
17. Ion saparation
the ion that go out from the ionization chamber will be isolated base on their mass-to-charge ratio.
18. Ionization chamber
the place where the ionization take place .
19. Ionization
The first stage in MS which the molecular atom of sample is bombarded with a beam of high-energy electron. Collision between these electrons and the sample result in loss of electrons from sample molecules and formation of positive ions, although rarely form a negative ions and radikal, but only the positive ions (cation) can be detected in MS.
20. Isotopic peak
Peak due to other isotope of the same chemical but different isotopic composition.
21. Mass spectrometer
An instrument hat analyzes ions according to their m/z ratio and measures electrically the number (abundance) of the ion.
22. Mass Spectrometry
Mass spectrometry is one of spectrometry method to identifying compounds based on their molecular weight. The sequenze in MS analysis is ionization, acceleration, deflection, adn detection which form a mass spectrum.
23. Mass spectrum
A spectrum obtained when ions (usually 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.
24. 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.
25. Metastable ion peak
Metastable ion peaks are usually broad peaks, and they frequently appear at non integral values of m/e.
26. 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.
27. Molecular ion
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.Radical cation
Molecular ion which contains an unpaired electron because it loss an electron as well as a positive charge. A positive charge usually use in MS.
28. 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.
29. 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.
30. 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.
31. Peak intensity
the height or area of a peak in a mas spectrum
32. Radical ion
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.
33. Relative abundance
Normalization to the base peak
34. Relative intensity
Ratio of the peak ntensity to that of the base peak.
35. 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.
Tidak ada komentar:
Posting Komentar