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Technical Description: System
Mass Spectrometer Parameters
B-16
Prima PRO & Sentinel PRO Mass Spectrometers User Guide
Figure B–11. Two mass peaks of adjacent molecular weight
and equal heights
A 5% Peak Height definition is exactly the same as the 10% Valley
definition and is illustrated in Figure B–12. This is an easier
definition to apply in practice since the peak width at 5% level of the
peak height can be easily measured. For example, in air when
examining the nitrogen 28 peak, the peak width at the 5% height can
be measured and related to the difference between mass 28 and mass
29. If the 5% width proved to be equal to 0.7 of the distance between
mass 28 and mass 29 (assuming the peak is centred exactly on 28),
then the resolving power is given by 28/0.7 = 40. This indicates that
the 10% Valley definition would apply to peaks of equal height at
masses 40 and 41.
Figure B–12. Comparison of 5% Peak Height definition and
10% Valley definition
Thermo Fisher Scientific
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