Indiana University

Andrew W Alexander

Martin F Jarrold

Aaron R Todd

Staci N Anthony

Deven L Shinholt

A CDMS may include an ion source to generate ions from a sample, a mass spectrometer to separate the generated ions as a function of ion mass-to-charge ratio, an electrostatic linear ion trap (ELIT) having a charge detection cylinder disposed between first and second ion mirrors, wherein ions exiting the mass spectrometer are supplied to the ELIT, a charge generator for generating free charges, a field free region between the charge generator and the charge detection cylinder, and a processor configured to control the charge generator, with no ions in the charge detection cylinder, to generate a target number of free charges and cause the target number of free charges to travel across the field-free region and into contact with the charge detection cylinder to deposit the target number of free charges thereon and thereby calibrate or reset the charge detection cylinder to a corresponding target charge level.

Instrument, including an electrostatic linear ion trap with charge detector reset or calibration, for separating ions

A CDMS may include an ELIT having a charge detection cylinder (CD), a charge generator for generating a high frequency charge (HFC), a charge sensitive preamplifier (CP) having an input coupled to the CD and an output configured to produce a charge detection signal (CHD) in response to a charge induced on the CD, and a processor configured to (a) control the charge generator to induce an HFC on the CD, (b) control operation of the ELIT to cause a trapped ion to oscillate back and forth through the CD each time inducing a charge thereon, and (c) process CHD to (i) determine a gain factor as a function of the HFC induced on the CD, and (ii) modify a magnitude of the portion of CHD resulting from the charge induced on the CD by the trapped ion passing therethrough as a function of the gain factor.

Charge detection mass spectrometer including gain drift compensation

Apparatus and method for calibrating or resetting a charge detector

A quadrupole mass filter and method for operating the filter are described. Sample ions, each having a mass-to-charge ratio, are passed to a quadrupole at least one AC voltage is applied thereto to separate the ions by incrementally varying a frequency of the at least one AC voltage within a first range of frequencies and, for each of at least some of the incremental frequencies in the first range of frequencies, incrementally varying an amplitude of the at least one AC voltage within a range of amplitudes, wherein each incremental frequency and incremental amplitude pair of the at least one AC voltage creates a different band pass filter in the quadrupole through which produced ions having a different corresponding mass-to-charge ratio pass to a detector.

Frequency and amplitude scanned quadrupole mass filter and methods

A quadrupole mass filter and method for operating the filter are described. AC voltages are applied to the quadrupole to separate ions based on mass-to-charge ratio. Frequency is scanned with a simultaneous amplitude scan. Ions are measured over a broad m/z range with high resolution. A resolving power of about 1,200 was demonstrated. Ions were observed for m/z values over 150,000 Th.

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Bloomington, IN, United States of America

Andrew W Alexander