Patent ID: 7297939

Claim:
A mass spectrometer comprising: an ion source; a mass filter/analyser arranged downstream of said ion source; an upstream ion detector arranged upstream of said mass filter/mass analyser; and a downstream ion trap arranged downstream of said mass filter/analyser, wherein said downstream ion trap is selected from the group consisting of: (i) an ion funnel including a plurality of electrodes having apertures therein through which ions are transmitted, wherein the diameter of said apertures becomes progressively smaller or larger; (ii) an ion tunnel including a plurality of electrodes having apertures therein through which ions are transmitted, wherein the diameter of said apertures remains substantially constant; (iii) a stack of plate, ring or wire loop electrodes; and (iv) a segmented rod set, wherein in a mode of operation said mass filter is operated in a wide band pass mode so as to transmit substantially all ions and said downstream ion trap is arranged to accumulate said ions.