Time of Flight Ion Trap Tandem Mass Spectrometer System

Abstract

Apparatus for delivering ions to the mass analyzer. The apparatus includes a time of flight ion guide, a pulsing device for receiving a continuous ion stream containing ions of different atomic mass and for delivering pulses of ions to the ion guide wherein ions in each of the pulses of ions exit the ion guide in ascending order of their atomic mass, and a gating device at the exit end of the ion guide for allowing ions of a predetermined atomic mass to pass to the mass analyzer.

1 . Apparatus for delivering ions to a mass analyzer comprising: 
 (a) a time of flight ion guide having an entrance end and an exit end;    (b) a pulsing device for receiving a continuous ion stream containing ions of different atomic mass and for delivering pulses of ions from said continuous stream of ions into the entrance end of said ion guide so that ions in each of said pulses of ions reach the exit end of said ion guide in ascending order of their atomic mass; and    (c) a gating device at the exit end of said ion guide operating in timed sequence with said pulsing device for allowing only ions of a predetermined atomic mass in each of said pulses of ions to pass through said gating device to said mass analyzer.    
   
   
       2 . The apparatus is recited in  claim 1 , wherein said gating device is a two part electric lens, said lens having an aperture, a first portion of said aperture being formed by one part of said electric lens and a second portion of said aperture being formed by the other part of said electric lens so that the electrical potential on each of said first and second portions can be independently controlled for selectively allowing ions to either pass through said aperture or be prevented from passing through said aperture.  
   
   
       3 . The apparatus in  claim 1 , further comprising refocusing means for refocusing ions passing through said gating device and for directing said refocussed ions into said mass analyzer.  
   
   
       4 . The apparatus as recited in  claim 3 , wherein said refocusing means comprises an ion lens.  
   
   
       5 . The apparatus as recited in  claim 1 , wherein said pulsing device comprises an ion lens.  
   
   
       6 . The apparatus as recited in  claim 1 , wherein said pulsing device comprises: 
 (a) a first ion lens for receiving said continuous ion stream; and    (b) a second ion lens between said first ion lens and said ion guide for delivering said pulses of ions to said ion guide.    
   
   
       7 . The apparatus as recited in  claim 6 , wherein said first and second ion lenses define a space therebetween for accumulating ions from said continuous ion stream.  
   
   
       8 . The apparatus as recited in  claim 6 , wherein said first ion lens has a first aperture and said second ion lens has a second aperture that is substantially smaller than said first aperture.  
   
   
       9 . The apparatus as recited in  claim 6 , wherein said ion guide is a radio frequency ion guide.  
   
   
       10 . The apparatus as recited in  claim 1 , further comprising a preliminary ion guide upstream of said pulsing apparatus for receiving said continuous ion stream and guiding said continuous ion stream to said time of flight ion guide.  
   
   
       11 . The apparatus as recited in  claim 10 , wherein said preliminary ion guide is a radio frequency ion guide.  
   
   
       12 .- 28 . (canceled)