Glossary: peak width at half height
Thermo Scientific Orbitrap Fusion Series Hardware Manual 95
peak width at half height The full width of a peak at
half its maximum height, sometimes abbreviated
FWHM.
precursor ion An electrically charged molecular
species that can dissociate to form fragments. The
fragments can be electrically charged or neutral
species. A precursor ion can be a molecular ion or an
electrically charged fragment of a molecular ion.
precursor mass The mass-to-charge ratio of a
precursor ion. The location of the center of a target
precursor-ion peak in mass-to-charge ratio (m/z)
units.
product ion An electrically charged fragment of an
isolated precursor ion.
product mass The mass-to-charge ratio of a product
ion. The location of the center of a target production
peak in mass-to-charge ratio (m/z) units.
profile data Data representing mass spectral peaks as
point-to-point plots, with each point having an
associated intensity value.
Q
qualitative analysis Chemical analysis designed to
determine the identity of the components of a
substance.
quantitative analysis Chemical analysis designed to
determine the quantity or concentration of a specific
substance in a sample.
R
reagent carrier gas Ultra-high-purity nitrogen gas
used to transfer the reagent to the reagent ion source
that is regulated by the backpressure regulator.
retention time (RT) The time after injection at which
a compound elutes. The total time that the
compound is retained on the chromatograph
column.
RF lens A multipole rod assembly that is operated
with only radio frequency (RF) voltage on the rods.
In this type of device, virtually all ions have stable
trajectories and pass through the assembly.
RF voltage (linear ion trap) An AC voltage of
constant frequency and variable amplitude that is
applied to the quadrupole rods of a linear ion trap
mass analyzer or to the rods of a multipole. Because
the frequency of this AC voltage is in the radio
frequency (RF) range, it is referred to as RF voltage.
S
scan Comprised of one or more microscans. Each
microscan is one mass analysis (ion injection and
storage/scan-out of ions) followed by ion detection.
After the microscans are summed, the scan data is
sent to the data system for display, storage, or both.
The process of ramping the amplitude of the RF and
DC voltages on the multipole rods in the mass
analyzer to transmit ions from the lowest mass to the
highest mass of a specified scan range.
scan mode and scan type combinations A function
that coordinates the three processes in the MS
detector: ionization, mass analysis, and ion detection.
You can combine the various scan modes and scan
types to perform a wide variety of experiments.
scan power The scan power n in MS
n
, which expresses
the number of stages of mass analysis. For example, a
scan power of n =1 corresponds to an MS
1
(or MS)
scan with one stage of mass analysis. A scan power of
n = 2 corresponds to an MS
2
(or MS/MS) scan with
two stages of mass analysis. A scan power of n =3
corresponds to an MS
3
scan with three stages of mass
analysis, and so on.
selected ion monitoring (SIM) scan type A scan type
where the mass spectrometer acquires and records ion
current following the isolation of a range of mass-to-
charge ratio values.
sheath gas The inner coaxial gas (nitrogen), which is
used in the API source to help nebulize the sample
solution into a fine mist as the sample solution exits
the ESI or APCI nozzle.
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