Technical data

88 Agilent 6200 Series TOF and 6500 Series Q-TOF LC/MS System Concepts Guide
3 Methods with Acquisition Parameters
Setup of TOF and Q-TOF reference mass correction (recalibration)
Number of required reference masses
To learn more about the underlying
calibration equation and
coefficients, see “TOF mass
calibration” on page 51.
With two unknowns, a minimum of two known values are
required to determine both A and t
o
. Practical considerations
also come into play. In order to get a good fit for both A and t
o
then at least one reference mass needs to be at a low mass value
and there needs to be at least one reference mass at a higher
mass. Standard analytical practice also suggests that the low
m/z and high m/z reference masses bracket the masses of
interest.
Specifically, the reference mass correction algorithm requires
that one mass be at or below 330 m/z with a second mass that is
at least 500 m/z above the low mass ion in order to correct t
o
and A terms. If these conditions are not satisfied but at least
one reference mass is found, then only the A term will be
re-calibrated.
Selecting/editing list of reference masses
When creating a new method, the Agilent MassHunter
Workstation Software provides separate lists of reference
masses for each polarity. You can use the already provided mass
list, or you can create or edit a new mass list by right-clicking
the arrow to the left of each row in the Ref Mass tab.
Parameters for a reference mass correction
To know more about Segments and
Experiments, see “Automatic TOF
and Q-TOF parameter changes
during a run” on page 73.
Scans To Average To increase the accuracy of the reference
mass correction, you can use a running average of the reference
mass values across several spectra. These mass values are used
in determining the corrected calibration coefficients. The
default number of spectra used is five. Only odd values are
allowed.
The software averages only spectra from the same scan group,
and therefore a spectral average spans a spectral cycle.
A spectral cycle contains one spectrum for each of the
Experiments defined in a given Segment.