Patent ID: 8481921

Claim:
A mass spectrometer comprising: a first mass selective ion trap comprising a first plurality of electrodes; a second mass selective ion trap comprising a second plurality of electrodes, wherein said second mass selective ion trap is arranged downstream of said first mass selective ion trap; and a device or ion gate for pulsing ions into said first ion trap, wherein, in use, ions are arranged to reside within said first ion trap in order to cool to near thermal energies by collisions with buffer gas molecules which are present within said first ion trap; wherein in a mode of operation a group of the ions that cooled to near thermal energies is arranged to be stored or trapped at an initial time T 0 in or within said first ion trap; said mass spectrometer further comprising: a control system which is arranged and adapted: (i) to cause said first ion trap to mass selectively eject ions of the group of ions having mass to charge ratios within a mass to charge ratio range of M 0 to M 1 out of said first ion trap during a first scan across the mass to charge ratio range, wherein at least some of said ions which are mass selectively ejected from or which emerge from said first ion trap are subsequently received by and stored or trapped in or within said second ion trap; and (ii) to cause said second ion trap to mass selectively eject at least some ions stored or trapped in or within said second ion trap out of said second ion trap during a second scan; wherein said second scan is commenced after said first scan is completed.