
Chapter 6 Acquiring Mass Spectra
6-10 PerSeptive Biosystems
6
Generated
calibration
If you are performing an internal standard calibration, the
software determines the constants as listed below:
Acquiring
calibration
standards
Use standards that are above and below the mass range of
interest.
To ensure that sample and standard peaks are similar in size
and shape, use the same acquisition conditions for sample
and standard, in particular:
• Instrument mode (linear or reflector)
• Signal intensity
• Laser intensity
• Voltages (Accelerating, Grid, and Guide Wire)
•Low Mass Gate
To obtain accurate mass values in the calibration, you need
well-shaped, symmetrical peaks. You may need to smooth or
noise filter peaks before calibrating. See the
Data Explorer
Software User’s Guide
, Section 5.7, Noise
Filtering/Smoothing, for more information.
Internal Standard
Calibration
Constant Value Used
One-point A Calculates from standard mass
t
0
Uses value from default
calibration
Two-point t
0
and A Calculates from standard mass
Three-point t
0
and A Calculates by linear
least-squares fit of the data
points from standard mass
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