| 摘要 |
The methods and devices which improve the trapping efficiency of injected ions for quadrupole ion traps. The methods and apparatus of the subject invention can be used in quadrupole ion trap mass spectrometry. The technique of the subject can, for example, vary the amplitude of the trap offset voltage with respect to RF phase angle and/or apply a time varying voltage to at least one lens external to the trap, thus altering the potential energy profile near the entrance to the trap and, therefore, altering the kinetic energy and/or arrival time of ions entering the ion trap. By controlling the kinetic energy and/or arrival time, a larger percentage of injected ions arrive at the ion trap with a kinetic energy conducive for trapping given the corresponding arrival RF phase angle. This allows a larger percentage of injected ions to be successfully trapped and therefore improves the sensitivity and analytical utility of the mass spectrometer.
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