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US 2013/0092830 A1Published application
Mass spectrometry with selective ion filtration by digital thresholding
AssigneeIbis Biosciences, Inc.
InventorsSteven A. Hofstadler, Jared J. Drader, Amy L. Schink
Life of this patent
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Abstract
The methods described herein generally relate to characterization of large analytes, such as biomolecules, by molecular mass analysis. Specifically, the methods are directed to molecular mass analysis of singly- or multiply-charged ions by selective ion filtering carried out by a digital thresholding process.
Claims21
A method of identifying a multiply-charged ion comprising:
- a) specifying a digital signal threshold on a mass spectrometer, wherein the mass spectrometer comprises:
- i) an ion detector;
- ii) a digitizer for converting an analog signal to a digital signal;
- iii) an analog signal transfer means for transferring an analog signal from the detector to the digitizer;
- and
- iv) a digital threshold filter, for setting a digital signal threshold, in digital data communication with the digitizer, in response to a digital signal input from the digitizer, independently outputting a digital signal to a data file only if the digital signal input is greater than the specified digital signal threshold;
- wherein upon a mass spectrometer measurement of the multiply-charged ion, the filtered digital signal output to the data file originates from the detection of the multiply-charged ion and excludes digital signal output from analog signals arising from singly-charged ions.
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11-22. (canceled)
A method of calibrating a mass spectrum of an analyte comprising:
- a) specifying a first digital signal threshold at a first member of a plurality of digital threshold filters, on a mass spectrometer, wherein the mass spectrometer comprises:
- i) an ion detector;
- ii) a digitizer for converting an analog signal to a digital signal;
- iii) an analog signal transfer means for transferring an analog signal from the detector to the digitizer;
- and
- iv) a plurality of digital threshold filters for setting a digital signal threshold, in digital data communication with the digitizer, in response to a digital signal input from
- the digitizer, independently outputting a digital signal to a corresponding data file only if
- the digital signal input is greater than the specified digital signal threshold;
- wherein the first digital signal threshold is specified such that digital signal output to a first data file comprises signals from the analyte and a calibrant ion;
- b) specifying a second digital signal threshold at a second member of the plurality of digital threshold filters wherein the second digital signal threshold is specified such that digital signal output to a second data file comprises signals from the analyte but not from the calibrant ion;
- c) subtracting the second data file from the first data file to obtain a calibration data file comprising a signal from the calibrant ion but not from the analyte;
- and
- d) using said calibration data file to calibrate the mass spectrum of the analyte.
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A system comprising a mass spectrometer comprising:
- an ion detector;
- a digitizer for converting an analog signal to a digital signal;
- an analog signal transfer means for transferring an analog signal from the detector to the digitizer;
- a plurality of digital threshold filters for setting a plurality of independent digital signal thresholds, each digital threshold filter in parallel electronic communication with the digitizer, each digital threshold filter in response to a digital voltage input from the digitizer independently outputting a digital voltage only if the digital voltage input is greater than the specified digital signal threshold;
- a plurality of data files;
- and
- a plurality of parallel digital signal output transferring means, each of which is in digital data communication with one of the digital threshold filters and a corresponding data file from the plurality of data files.
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Dependencies are inferred from the claim text.