Mass spectrometer

Abstract

A closed-loop ion guide 1 is disclosed comprising a plurality of electrodes having apertures through which ions are transmitted in use. Ions are injected into the closed-loop ion guide 1 and may make several circuits of the closed-loop ion guide 1 before being ejected from the ion guide 1 . In a mode of operation the ion guide 1 may be arranged to separate ions temporally according to their ion mobility.

1 . An ion mobility spectrometer or ion mobility separator portion comprising a closed-loop ion guide comprising a plurality of electrodes. 
     
     
         2 . An ion mobility spectrometer or ion mobility separator portion as claimed in  claim 1 , wherein in a mode of operation ions are arranged to make multiple circuits or rotations of or around said closed-loop ion guide. 
     
     
         3 . An ion mobility spectrometer or ion mobility separator portion as claimed in  claim 1 , wherein in a mode of operation at least 50%, 60%, 70%, 80%, 90%, 95% or 100% of ions within said closed-loop ion guide are arranged to move in substantially the same direction or rotate in substantially the same sense along or around said closed-loop ion guide at a particular moment in time. 
     
     
         4 . An ion mobility spectrometer or ion mobility separator portion as claimed in  claim 1 , wherein a non-zero DC voltage gradient is maintained in use across one or more sections or portions of said ion guide and wherein the integral of the axial DC voltage gradient around said closed-loop ion guide is substantially zero. 
     
     
         5 . An ion mobility spectrometer or ion mobility separator portion as claimed in  claim 1 , wherein said ion guide comprises a curved, labyrinthine, tortuous, serpentine or circuitous ion guiding path which forms a circuit or circular path or convoluted path. 
     
     
         6 . An ion mobility spectrometer or ion mobility separator portion as claimed in  claim 1 , wherein in a mode of operation ions are arranged to rotate or circulate around said closed-loop ion guide. 
     
     
         7 . An ion mobility spectrometer or ion mobility separator portion as claimed in  claim 1 , wherein said plurality of electrodes comprise electrodes having apertures through which ions are transmitted in use. 
     
     
         8 . An ion mobility spectrometer or ion mobility separator portion as claimed in  claim 1 , wherein said ion guide comprises a segmented rod set ion guide. 
     
     
         9 . An ion mobility spectrometer or ion mobility separator portion as claimed in  claim 1 , wherein said ion guide comprises a plurality of plate electrodes, wherein a plurality of groups of electrodes are arranged along the axial length of said ion guide. 
     
     
         10 . An ion mobility spectrometer or ion mobility separator portion as claimed in  claim 1 , further comprising means for driving or urging ions along or around at least 1%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95% or 100% of the length or ion guiding path of said ion guide. 
     
     
         11 . An ion mobility spectrometer or ion mobility separator portion as claimed in  claim 1 , further comprising means arranged to maintain a constant non-zero DC voltage gradient along at least 1%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95% or 100% of the length or ion guiding path of said ion guide. 
     
     
         12 . An ion mobility spectrometer or ion mobility separator portion as claimed in  claim 1 , wherein in use a buffer gas is provided within one or more sections of said ion guide. 
     
     
         13 . An ion mobility spectrometer or ion mobility separator portion as claimed in  claim 1 , further comprising one or more mass filters arranged upstream of and/or within and/or downstream of said closed-loop ion guide. 
     
     
         14 . An ion mobility spectrometer or ion mobility separator portion as claimed in  claim 1 , further comprising a collision, fragmentation or reaction device arranged upstream of and/or within and/or downstream of said closed-loop ion guide. 
     
     
         15 . An ion mobility spectrometer or ion mobility separator portion as claimed in  claim 1 , further comprising a mass analyser arranged upstream of and/or within and/or downstream of said closed-loop ion guide. 
     
     
         16 . A method of ion mobility spectrometry or separating ions according to ion mobility, comprising:
 guiding ions through a closed-loop ion guide comprising a plurality of electrodes.   
     
     
         17 . A closed-loop ion guide comprising an ion mobility spectrometer or separator portion, section or stage wherein ions are caused to separate temporally according to their ion mobility in said ion mobility spectrometer or separator portion, section or stage. 
     
     
         18 . A mass spectrometer comprising a closed-loop ion guide as claimed in  claim 17 .