Micromass Quattro Ultima, Руководство пользователя

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Incorrect Calibration
If the suggested calibration parameters are used, and providing that good calibration
data have been acquired, then the instrument should be calibrated correctly. However
in some circumstances it is possible to meet the calibration criteria without matching
the correct peaks. This situation is unusual, but it is always sensible to examine the
on-screen calibration report to check that the correct peaks have been matched. These
errors may occur when the following parameters are set:
Intensity threshold
set to 0
Initial error too high (>2.0)
Peak window too high (>1.5)
Maximum Std Deviation
too high (>0.2).
If the acquired spectrum looks like the reference spectrum and all of the expected
peaks are highlighted then the calibration is OK.
An alternative cause of incorrect calibration is from contamination or background
peaks. If a contamination or background peak lies within one of the peak matching
windows, and is more intense than the reference peak in that window, then the wrong
peak is selected. Under some conditions this may happen with PEG. There are two
ways to counter this:
•
If the reference peak is closer to the centre of the peak window then the peak
window can be narrowed until the contamination peak is excluded. Take care to
ensure that no other reference peak is excluded.
•
If the reference peak is not closer to the centre of the peak window, or if by
reducing the window other reference peaks are excluded, then the calibration can
be edited manually.
Mass Calibration
Page 120
Quattro Ultima
User's Guide