Methods and apparatus for external accumulation and photodissociation of ions prior to mass spectrometric analysis

Abstract

The present invention discloses novel methods and apparatuses for mass spectrometry. In the methods and apparatuses of the invention, ions are accumulated in an ion reservoir and dissociated with coherent radiation prior to mass analysis. These methods and apparatuses are amenable to mass spectrometric analysis of biomolecules and are particularly useful for the sequencing of oligonucleotides, peptides and oligosaccharides.

What is claimed is:  
     
         1 . A method of inducing dissociation of molecular ions prior to analysis in a mass analyzer of a mass spectrometer, comprising the steps of: 
 a) generating said molecular ions by ionization;    b) accumulating said ions in an ion reservoir; and    c) exposing said ions in said ion reservoir to coherent radiation to dissociate said ions prior to mass analysis in a mass analyzer of a mass spectrometer.    
     
     
         2 . The method of  claim 1  further comprising transporting said dissociated ions to a mass analyzer of a mass spectrometer.  
     
     
         3 . The method of  claim 1  wherein said accumulating of ions occurs in a m/z range of from about 50 to about 100,000.  
     
     
         4 . The method of  claim 1  wherein said ion reservoir is a rf trap or Penning trap.  
     
     
         5 . The method of  claim 4  wherein said rf trap is a rf-multi-pole ion reservoir.  
     
     
         6 . The method of  claim 5  wherein said rf-multi-pole ion reservoir is a quadrupole, hexapole or octapole ion reservoir.  
     
     
         7 . The method of  claim 1  wherein said ion reservoir is evacuated to 10 −3  to 10 −6  torr.  
     
     
         8 . The method of  claim 1  wherein said coherent radiation is emitted from a laser.  
     
     
         9 . The method of  claim 8  wherein said laser is an infrared laser.  
     
     
         10 . The method of  claim 2  wherein said transporting is effected by either removing or reversing an electric field generated by gate electrodes on either side of said ion reservoir.  
     
     
         11 . The method of  claim 2  wherein said mass analyzer is a trapped ion cell of a Fourier transform ion cyclotron mass spectrometer, a time-of-flight mass spectrometer, a quadrupole ion trap mass spectrometer, a quadrupole mass analyzer, or a magnetic/electric sector mass spectrometer.  
     
     
         12 . An apparatus for dissociation of ions in mass spectrometry comprising: 
 a) an ion reservoir for receiving and accumulating ions produced from an ion source; and    b) a coherent radiation source in operative association with said ion reservoir and which emits coherent radiation to dissociate ions within said ion reservoir prior to analysis in a mass analyzer of a mass spectrometer.    
     
     
         13 . The apparatus of  claim 12  wherein said ion reservoir is a rf trap or Paul trap.  
     
     
         14 . The apparatus of  claim 13  wherein said rf trap is a rf-multi-pole ion reservoir.  
     
     
         15 . The apparatus of  claim 14  wherein said rf-multi-pole ion reservoir is a quadrupole, hexapole or octapole ion reservoir.  
     
     
         16 . The apparatus of  claim 12  wherein said ion reservoir is evacuated to 10 −3  to 10 −6  torr.  
     
     
         17 . The apparatus of  claim 12  wherein said coherent radiation is emitted from a laser.  
     
     
         18 . The apparatus of  claim 17  wherein said laser is an infrared laser.  
     
     
         19 . A mass spectrometer comprising: 
 a) ion source;    b) ion reservoir;    c) first conduit connecting said ion source to said ion reservoir for transporting ions from said ion source to said ion reservoir;    d) coherent radiation source in operative association with said ion reservoir which emits coherent radiation to dissociate ions within said ion reservoir;    e) mass analyzer; and    f) second conduit connecting said ion reservoir to said mass analyzer for transporting ions between said ion reservoir and said mass analyzer.    
     
     
         20 . The apparatus of  claim 19  wherein said ion reservoir is a rf trap or Paul trap.  
     
     
         21 . The apparatus of  claim 20  wherein said rf trap is a rf-multi-pole ion reservoir.  
     
     
         22 . The apparatus of  claim 21  wherein said rf-multi-pole ion reservoir is a quadrupole, hexapole or octapole ion reservoir.  
     
     
         23 . The apparatus of  claim 19  wherein said ion reservoir is evacuated to 10 −3  to 10 −6  torr.  
     
     
         24 . The apparatus of  claim 19  wherein said coherent radiation is emitted from a laser.  
     
     
         25 . The apparatus of  claim 24  wherein said laser is an infrared laser.  
     
     
         26 . The apparatus of  claim 19  wherein said transporting ions from said ion reservoir to said mass analyzer is effected by either removing or reversing an electric field generated by gate electrodes on either side of said ion reservoir.  
     
     
         27 . The apparatus of  claim 19  wherein said mass analyzer is a trapped ion cell of a Fourier transform ion cyclotron mass spectrometer, a time-of-flight mass spectrometer, a quadrupole ion trap mass spectrometer, a quadrupole mass analyzer, or a magnetic/electric sector mass spectrometer.