Patent ID: 6906319

Claim:
A method of mass spectrometry, comprising the steps of: providing a packet or pulse of ions; temporally separating at least some of the ions in said packet or pulse according to their ion mobility in a first device; mass filtering at least some of said ions according to their mass to charge ratio in a second device; progressively varying a mass filtering characteristic of said second device so that ions having a first charge state are onwardly transmitted in preference to ions having a second different charge state; trapping some ions having said first charge state in a first ion trap; releasing a first group of ions from said first ion trap and orthogonally accelerating said first group of ions a first predetermined time later; mass analysing said first group of ions; trapping further ions having said first charge state in said first ion trap; releasing a second group of ions from said first ion trap and orthogonally accelerating said second group of ions a second different predetermined time later; and mass analysing said second group of ions.