Instrument for separating ions including an electrostatic linear ion trap to simultaneously trap multiple ions

An instrument for separating ions, comprising:

• an ion source configured to generate ions from a sample,
• a first mass spectrometer configured to separate the generated ions as a function of mass-to-charge ratio,
• an ion dissociation stage positioned to receive ions exiting the first mass spectrometer and configured to dissociate ions exiting the first mass spectrometer,
• a second mass spectrometer configured to separate dissociated ions exiting the ion dissociation stage as a function of mass-to-charge ratio, and
• a charge detection mass spectrometer (CDMS) coupled in parallel with and to the ion dissociation stage such that the CDMS can receive ions exiting either of the first mass spectrometer and the ion dissociation stage, the CDMS comprising (i) at least one ion separation instrument configured to separate ions as a function of at least one molecular characteristic, (ii) an electrostatic linear ion trap (ELIT) including a pair of coaxially aligned ion mirrors and an elongated charge detection cylinder disposed therebetween and coaxially aligned therewith such that a longitudinal axis of the ELIT passes centrally through each, a first one of the pair of ions mirror defining an ion inlet aperture about the longitudinal axis through which the beam of separated ions enters the ELIT, (iii) at least one voltage source operatively coupled to the pair of ion mirrors and configured to produce voltages for selectively establishing electric fields therein configured to trap within the ELIT a plurality of ions in the entering beam of separated ions and to cause the plurality of trapped ions to oscillate back and forth between the pair of ion mirrors each time passing through the charge detection cylinder, and (iv) means for controlling a trajectory of the beam of separated ions entering the ion inlet aperture of the ELIT to cause the plurality of ions subsequently trapped within the ELIT to oscillate therein with a corresponding plurality of different planar ion oscillation trajectories angularly offset from one another about the longitudinal axis with each extending along the longitudinal axis and crossing the longitudinal axis in each of the pair of ion mirrors or a corresponding plurality of different cylindrical ion oscillation trajectories radially offset from one another about the longitudinal axis to form a plurality of nested cylindrical trajectories each extending along the longitudinal axis,
• wherein masses of precursor ions exiting the first mass spectrometer are measured using the CDMS, mass-to-charge ratios of dissociated ions of precursor ions having mass values below a threshold mass are measured using the second mass spectrometer, and mass-to-charge ratios and charge values of dissociated ions of precursor ions having mass values at or above the threshold mass are measured using the CDMS.

A method of simultaneously measuring at least two ions in a beam of ions supplied to an electrostatic linear ion trap (ELIT) including a pair of coaxially aligned ion mirrors and an elongated charge detection cylinder disposed therebetween and coaxially aligned therewith such that a longitudinal axis of the ELIT passes centrally through each, wherein a first one of the pair of ions mirror defines an ion inlet aperture about the longitudinal axis through which the supplied beam of ions enters the ELIT, the method comprising:

• controlling at least one voltage source to apply voltages to the pair of ion mirrors to establish an ion transmission electric field therein to pass the beam of ions supplied to the ion inlet aperture of the ELIT through each of the pair of ion mirrors and through the charge detection cylinder and through an ion exit defined by a second one of the pair of ion mirrors, wherein each ion transmission electric field is configured to focus ions passing therethrough toward the longitudinal axis,
• controlling the at least one voltage source to modify the voltages applied to the pair of ion mirrors to establish an ion reflection electric field therein to trap within the ELIT at least two of the ions in the beam of ions supplied to the ion inlet aperture of the ELIT, wherein each ion reflection electric field is configured to cause ions entering a respective one of the pair of ion mirrors from the charge detection cylinder to stop and accelerate in an opposite direction back through the charge detection cylinder and toward the other of the pair of ion mirrors while also focusing the ions toward the longitudinal axis, and
• controlling a trajectory of the beam of ions entering the ion inlet aperture of the ELIT to cause the at least two ions subsequently trapped within the ELIT to oscillate therein with at least two different planar ion oscillation trajectories angularly offset from one another about the longitudinal axis with each extending along the longitudinal axis and crossing the longitudinal axis in each of the pair of ion mirrors.

A method of simultaneously measuring at least two ions in a beam of ions supplied to an electrostatic linear ion trap (ELIT) including a pair of coaxially aligned ion mirrors and an elongated charge detection cylinder disposed therebetween and coaxially aligned therewith such that a longitudinal axis of the ELIT passes centrally through each, wherein a first one of the pair of ions mirror defines an ion inlet aperture about the longitudinal axis through which the supplied beam of ions enters the ELIT, the method comprising:

• controlling at least one voltage source to apply voltages to the pair of ion mirrors to establish an ion transmission electric field therein to pass the beam of ions supplied to the ion inlet aperture of the ELIT through each of the pair of ion mirrors and through the charge detection cylinder and through an ion exit defined by a second one of the pair of ion mirrors, wherein each ion transmission electric field is configured to focus ions passing therethrough toward the longitudinal axis,
• controlling the at least one voltage source to modify the voltages applied to the pair of ion mirrors to establish an ion reflection electric field therein to trap within the ELIT at least two of the ions in the beam of ions supplied to the ion inlet aperture of the ELIT, wherein each ion reflection electric field is configured to cause ions entering a respective one of the pair of ion mirrors from the charge detection cylinder to stop and accelerate in an opposite direction back through the charge detection cylinder and toward the other of the pair of ion mirrors while also focusing the ions toward the longitudinal axis, and
• controlling a trajectory of the beam of ions entering the ion inlet aperture of the ELIT to cause the at least two ions subsequently trapped within the ELIT to oscillate therein with at least two different cylindrical ion oscillation trajectories radially offset from one another about the longitudinal axis to form at least two nested cylindrical ion oscillation trajectories each extending along the longitudinal axis.