Caption: FIGURE 4: Peaks of mass-to-charge ratio
(m/z) 6,626 after purification.
The mass-to-charge ratio
(m/z) of a peptide precursor ion is selected and fragmented into product ions.
The ionized proteins then are accelerated in an electrical field and the mass-to-charge ratio
is deduced from their velocity.
separation, analyzer detection, and ionization of protein molecules.
Ions of different mass-to-charge ratios
are then resolved in the time domain based upon their velocities through a field-free flight tube.
The ionized secondary particles extracted from the surface are analyzed with respect to energy and then separated according to their mass-to-charge ratio
In at least one case the author conforms to accepted usage, e.g., the mass-to-charge ratio
(m/z) is defined as a dimensionless quantity, although the physics of the accepted terminology are questionable because a quantity so defined cannot be used in equations of motion for charged particles.
Just as a monochromator in emission/absorption spectrometry separates light according to wavelengths, a quadrupole mass analyzer used in AMS separates the ions of various elements into their mass-to-charge ratio
1B), and the mass spectra of all 96 fractions are combined, producing a two-dimensional display of peptide masses in which the abscissa displays the mass-to-charge ratio
, the ordinate is determined by the retention time on the RP-HPLC column, and the signal intensity is depicted by color saturation (Fig.
Ions of only one particular mass-to-charge ratio
will traverse the mass filter in a tight and stable spiral and be collected by the detector.
In selected ion storage, an ion of a single mass-to-charge ratio
(m/z) is retained in the QIT at a time, much like SIM operation of a quadrupole mass filter.
These ions are separated by the mass spectrometer according to their mass-to-charge ratio
(m/z), producing a spectrum on an m/z scale.