Quadrapole Mass Spectrometers of MS/MS

Figure 27. The Triple Quadrapole Mass Spectrometer

The sample enters the ion source and is usually fragmented by either an electron impact or chemical ionization process. In the first analyzer the various charged fragments are separated in the usual way, which then pass into the second quadrapole section sometimes called the collision cell. The first quadrapole acts as a simple mass spectrometer.

Instead of the ions passing to a sensor, the ions pass into a second mass spectrometer. It is in this segment a specific ion can be selected for further study. In the center quadrapole section the selected ion is further fragmented by collision ionization and the new fragments then pass into the third quadrapole which functions as the second analyzer. The second analyzer segregates the new fragments into their individual masses, which are detected by the sensor, producing the mass spectrum. In this way, the exclusive mass spectrum of a particular molecule or fragment ion can be obtained from the myriad of ions that may be produced from the sample in the first analyzer. It is seen that this is an extremely powerful analytical system that can handle exceedingly complex mixtures and very involved molecular structures. The system has a adequate resolving power and is valuable for structure elucidation.