Micromass Quattro Ultima, User Manual

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It is possible to select the daughter mass to be greater than the parent
(precursor) mass. In this case ions which have gained mass in the collision cell,
or are of higher mass to charge ratio, are detected. This can occur when a
multiply charged ion fragments and loses a charge.
Parent
This mode is used to look for the parent of a particular fragment.
MS2 is set to the mass of the fragment, using
Parents of
, and is not scanned.
Start and End specify the mass range over which MS1 is scanned. Start is normally
set just below Parents of , and End to a value above the highest expected parent
mass.
There are often several masses from which a daughter may come, so that any
one fragment is derived from a number of different peaks.
MS2
In this mode MS2 is resolving, while MS1 transmits ions over a wide mass range.
While this scanning mode can be used for acquiring data it is mostly used in the tune
window, for setting and optimising the acquisition conditions.
Neutral Loss
In this mode, the peak in a spectrum that gives the neutral loss specified in Loss of is
detected. The precursor mass is scanned in MS1, and MS2 is scanned at this mass less
the neutral loss mass. Starting masses are therefore detected on the mass scale of MS1.
Start (for MS1) should be greater than Loss of to give MS2 a valid start mass.
Neutral Gain
This is an infrequently used mode, since the mass selected by MS2 is higher than that
of MS1. It is applicable to studies where a precursor ion gains mass by ion molecule
reaction or where multiply charged ions fragment into particles with a higher
m
value.
Data Acquisition
Page 91
Quattro Ultima
User's Guide