A multipole ion guide includes a plurality of electrodes disposed about a longitudinal axis of the device so as to define an ion transmission volume for transmitting ions along a length of the device between opposite inlet and outlet ends. An electronic controller is operably connected to an RF power source and to at least some of the electrodes and is configured to apply at least an RF potential to the electrodes. During use the electrodes generate an RF-only field along a first portion of the device and an axial DC field along a second portion of the device. Ions are focused radially inward toward the longitudinal axis of the device by the RF-only field within the first portion of the device prior to and/or subsequent to experiencing the axial DC field within the second portion of the device.

A mass selective ion trapping device includes a linear ion trap and a RF control circuitry. The ion trap includes a plurality of trap electrodes configured for generating a quadrupolar trapping field in a trap interior and for mass selective ejection of ions from the trap interior. The RF control circuitry is configured to apply a balanced AC voltage to the trap electrodes during a first period of time such that an AC voltage applied to a first pair of trap electrodes is of the same magnitude and of opposite sign to an AC voltage applied to a second pair of trap electrodes; apply unbalanced RF voltage to the second pair of trap electrodes during a second period of time; ramp the balanced AC voltage down and the unbalanced RF voltage up during a transition period; and eject ions from the linear ion trap after the second period of time.

The invention generally relates to systems and methods for isolating a target ion in an ion trap. In certain aspects, the invention provides a system that includes a mass spectrometer having an ion trap, and a central processing unit (CPU). The CPU includes storage coupled to the CPU for storing instructions that when executed by the CPU cause the system to apply a dual frequency waveform to the ion trap that ejects non-target ions from the ion trap while retaining a target ion in the ion trap.

A charge detection mass spectrometer may include an ion source, an electrostatic linear ion trap (ELIT) including a charge detection cylinder disposed between a pair of coaxially aligned ion mirrors, means for selectively establishing electric fields within the ion mirrors configured to cause the trapped ions in the ELIT to oscillate back and forth between the ion mirrors each time passing through the charge detection cylinder, and means for controlling a trajectory of the beam of ions entering the ELIT to cause the subsequently trapped ions to oscillate with different planar ion oscillation trajectories angularly offset from one another about the longitudinal axis with each extending along and crossing the longitudinal axis in each of the ion mirrors or with different cylindrical ion oscillation trajectories radially offset from one another about the longitudinal axis to form nested cylindrical trajectories each extending along the longitudinal axis.

Methods and apparatus are disclosed for reducing ion reflections between multipole segments in a mass spectrometer by matching the effective potential between the two segments. Mass spectrometers having at least two multipole segments separated from each other along a longitudinal axis of the mass spectrometer such that a boundary region exists through which ions are drawn from an upstream segment to a downstream segment, and wherein each multipole segment further includes a set of spaced-apart rod-shaped electrodes disposed around the longitudinal axis and having a field radius defined by an inscribed circle between the innermost portions of each electrode. Effective potential matching can be achieved by either supplying RF signals of different amplitudes to each segment and/or by modifying the field strength of the segments. In one embodiment, the multipole segments are configured such that the upstream multipole segment has a smaller field radius than the downstream segment.

A multipole ion guide includes a plurality of electrodes disposed about a longitudinal axis of the device so as to define an ion transmission volume for transmitting ions along a length of the device between opposite inlet and outlet ends. An electronic controller is operably connected to an RF power source and to at least some of the electrodes and is configured to apply at least an RF potential to the electrodes. During use the electrodes generate an RF-only field along a first portion of the device and an axial DC field along a second portion of the device. Ions are focused radially inward toward the longitudinal axis of the device by the RF-only field within the first portion of the device prior to and/or subsequent to experiencing the axial DC field within the second portion of the device.

The invention relates to the detection of fatty acids. In a particular aspect, the invention relates to methods for detecting very long chain fatty acids and branched chain fatty acids by mass spectrometry.

A device for controlling trapped ions includes an ion trap, a plurality of field electrodes configured to control ions in the ion trap, and a controller chip. The controller chip includes at least one delta-sigma digital to analog converter (DS-DAC) module including a DS-DAC circuit configured to receive a digital data stream, convert the digital data stream to analog control voltages, and supply the analog control voltages to the field electrodes.

An optimization control system may receive mass spectra of ions emitted from an ionization emitter toward an inlet of a mass spectrometer and control, based on the mass spectra, an automated motion system to adjust a position of the emitter relative to the inlet.

The invention generally relates to ion traps and methods of use thereof. In certain embodiments, the invention provides a system that includes a mass spectrometer including an ion trap, and a central processing unit (CPU). The CPU has storage that is coupled to the CPU for storing instructions that when executed by the CPU cause the system to apply a constant radio frequency (RF) signal to the ion trap, and apply a first alternating current (AC) signal to the ion trap the frequency of which varies as a function of time.