MS/MS operating modes 1-13
Multiple reaction monitoring mode
Typical application
You typically use MRM to quantify known analytes in complex samples:
• Drug metabolite and pharmacokinetic studies.
• Environmental, for example, pesticide and herbicide analysis.
• Forensic or toxicology, for example, screening for target drugs in sport.
MRM does not produce a spectrum because only one transition is monitored at
a time. As in SIR, a chromatogram is produced.
Constant neutral loss mode
Constant neutral loss mode detects the loss of a specific neutral fragment or
functional group from an unspecified precursor(s).
The scans of MS1 and MS2 are synchronized. When MS1 transmits a specific
precursor ion, MS2 “looks” to see whether that precursor loses a fragment of a
certain mass. If it does, the loss registers at the detector.
In constant neutral loss mode, the spectrum shows the masses of all
precursors that actually lost a fragment of a certain mass.
MS1
Static (at precursor mass)
MS2
Static (at product mass)
Collision cell
Pass all masses
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