Patent ID: 8513594

Claim:
A method of mass spectrometry comprising the steps of, in a first cycle: (a) storing sample ions in a first ion storage device, the first ion storage device having an exit aperture and a spatially separate ion transport aperture; (b) ejecting the stored ions out of the exit aperture along a first direction of travel defining an ion ejection direction; (c) transporting the ejected ions into an ion selection device which is spatially separated from the first ion storage device; (d) carrying out ion selection within the spatially separated ion selection device; (e) returning at least some of the ions ejected from the first ion storage device, or their derivatives, back from the spatially separate ion selection device to the first ion storage device, following the step (d) of ion selection; (f) receiving the returned ions through the ion transport aperture of the first ion storage device from a second general direction of travel defining an ion capture direction, the ion capture direction being substantially non parallel with respect to the ion ejection direction, and wherein the ion path of the returned ions does not extend through the exit aperture; and (g) storing the received ions in the first ion storage device.