44 Agilent 6400 Series Triple Quad LC/MS Concepts Guide
3 Agilent Triple Quadrupole MS and Sensitivity
Example of chemical noise reduction
Step 3 After MS1 (Q1), fragment ions are generated in the
collision cell. The corresponding MS/MS spectrum is shown
below the collision cell.
Step 4 Particular fragment ions can be selected to pass
through the MS2 (Q3) quadrupole. These are selected for
quantitation and confirmation. For example, the product ion at
m/z 158 is more intense than the product ion at m/z 191.
Therefore, the MRM transition 210 to 158 would be used for
quantitation and the 210 to 191 transition would be used for
confirmation, where the m/z 191 ion is considered a qualifier
ion.
The second stage of selectivity using the MS2 (Q3) quadrupole
removes much of the chemical background. Typically, the
chance of an isobaric interference at the same exact mass as the
fragmentation ion is remote.
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