14 Agilent 6400 Series Triple Quad LC/MS Concepts Guide
2 Inner Workings – Triple Quadrupole MS versus Single Quadrupole MS 
Single quadrupole MS operation 
Single quadrupole MS operation
To better understand the specific hardware features of the 
Agilent 6400 Series Triple Quadrupole Mass Spectrometer, this 
section first reviews the fundamental aspects of the single 
quadrupole mass spectrometer.
Design for a single quadrupole mass spectrometer
Mass spectrometry is based on the analysis of ions moving 
through a vacuum.
The ionization of a sample occurs in the ion source that is 
shown, schematically, on the left. The ions are analyzed by 
a mass analyzer (mass filter) that controls the motion of the 
ions as they travel to the detector to be converted into actual 
signals. 
m/z – mass/charge ratio The quadrupole mass analyzer consists of four parallel rods to 
which specific DC and RF voltages are applied. These rods filter 
out all ions except those of one or more particular m/z values as 
determined by the voltages applied. 
Figure 1 Schematic for single quadrupole mass spectrometer