Precursor (Parent) Ion Mode; Multiple Reaction Monitoring Mode - Waters Xevo TQ-S Operator's, Overview And Maintenance Manual

Precursor (parent) ion mode

Precursor ion mode:
Typical application
You typically use the precursor ion mode for structural elucidation—that is, to
complement or confirm product scan data—by scanning for all the precursors
of a common product ion.

Multiple reaction monitoring mode

Multiple reaction monitoring (MRM) mode is the highly selective MS/MS
equivalent of SIR. Because both MS1 and MS2 are static, greater dwell time
on the ions of interest is possible, so the sensitivity achieved is better,
compared with scanning-mode MS/MS. This mode is the most commonly used
acquisition mode for quantitative analysis, allowing the compound of interest
to be isolated from the chemical background noise.
Multiple reaction monitoring mode:
1-12 Waters Xevo TQ-S Overview
MS1
Scanning
MS1
Static (at precursor mass)
Collision cell MS2
Pass all masses Static (at product mass)
Collision cell MS2
Pass all masses Static (at product mass)