Patent ID: 8853622

Claim:
A tandem mass spectrometer, comprising: a collision cell comprising an ion inlet for receiving ions, the collision cell having a collision gas in its interior during operation of the mass spectrometer for causing at least a portion of the ions to undergo collisions and to form product ions by fragmentation; a two-dimensional ion trap comprising a trapping region including an ion entrance for receiving ions having a mass-to-charge ratio within a first range of values, the ion trap being operable to mass-selectively eject, through an ion exit, ions having a mass-to-charge ratio within a second range of values that is narrower than the first range of values, the trapping region being curved concavely toward the ion inlet of the collision cell for focusing ejected ions toward the ion inlet of the collision cell; and, a mass analyzer in communication with the collision cell for receiving the product ions therefrom and for generating product ion mass spectra.