Introducing the MSQ
_______________________________________________________________________The Data System
Profile
With profile acquisition, data is not “centroided” into sticks. Instead, the
signal received by the interface electronics is stored to give an analog
intensity profile of the data being acquired for every scan (see Figure 1-27).
Profile acquisition enables mass spectral peak width and resolution to be
examined and measured. For example, the resolution between an ion and its
isotope(s) or multiply charged ions can be seen and measured, if necessary.
This is most useful in the case of protein and peptide analysis, where
multiply charged ions are formed.
As data is being written to disk at all times (even when there are no peaks
being acquired), profile data acquisition places an extra burden on the
acquisition system in comparison to centroided acquisition. Profile data files
tend to be significantly larger than centroided ones and the scan speeds used
tend to be slower than when acquiring centroided data.
275
300
325
350
375
400
425
450
475
500
525
m/z
0
100
%
503
281
325
283
504
Figure 1-27. Full scan profile spectrum of D-raffinose
___________________________MSQ Hardware Manual ___________________________
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