Radiant energy – Ionic separation or analysis – Methods
Reexamination Certificate
2005-06-21
2005-06-21
Wells, Nikita (Department: 2881)
Radiant energy
Ionic separation or analysis
Methods
C281S013000
Reexamination Certificate
active
06909089
ABSTRACT:
The invention solves the problem of artifact ghost peaks which can sometimes arise in mass spectrometers that employ a quadrupole rod set for both trapping and mass analyzing the trapped ions. The problem arises as a result of randomly distributed voltage gradients along the length of the rods. Three solutions are presented. The first approach involves improving the conduction characteristics of the rod sets. The second approach involves the application of at least one continuous axial DC field to the trapping quadrupole rod set in order to urge ions towards a pre-determined region of the trap, thereby avoiding voltage gradients. The third approach involves the application of one or more discrete axial fields to create one or more potential barriers along the axial dimension of the trap (in addition to the barriers used to initially trap the ions). These barriers prevent ions of differing voltage gradients from equilibrating with one another.
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Collings Bruce A.
Hager James
Londry Frank R.
Stott William R.
Barnes & Thornburg LLP
Martin Alice O.
MDS Inc.
Quash Anthony
Wells Nikita
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