Patent ID: 7714279

Claim:
A method for operating a time-of-flight mass spectrometer in which ions from an RF ion guide are injected, via a lens system, into a pulser that operates periodically, comprising: operating at least a part of the ion guide as an ion storage device in which ions of all masses are stored together in a single trapping region and from which, after the ion storage device has been filled and before additional ions are introduced into the storage device, groups of ions are mass-selectively extracted over several periods of the pulser, wherein the ions in each extracted group have masses within a mass range and wherein the mass range is varied so that ion groups including the lightest ions are first extracted, and in subsequent pulser periods, ion groups including increasingly heavier ions are extracted; and during each pulser period, accelerating an extracted group of ions without fragmenting the ions and injecting the accelerated group of ions into the pulser, using acceleration and injection parameters that are changed according to the mass range of the ions within that extracted group of ions in order to optimize ion injection into the pulser.