ESTIMATION OF ION CYCLOTRON RESONANCE PARAMETERS IN FOURIER TRANSFORM MASS SPECTROMETRY
First Claim
1. A method for accurately estimating Fourier Transform mass spectrometry signal parameters comprising:
- (i) obtaining a time-series of voltage or current measurements of the time-dependent image charge generated upon two or more detector plates by whose motion inside an analyzer is essentially sinusoidal in one or more component directions;
(ii) taking a discrete Fourier transform of the obtained time-series to produce a spectrum; and
(iii) constructing maximum-likelihood estimates of a) frequency (f0), b) amplitude |α
|, c) phase (arg(α
)), and d) decay time constant (τ
) Fourier Transform mass spectrometry signal parameters from the acquired Fourier Transform mass spectrometry data using as a time-domain model an exponentially decaying sinusoid that has been truncated white Gaussian noise or its equivalent representation as a complex-valued discrete Fourier transform,wherein the Fourier Transform mass spectrometry data is represented either as a time-series of measurements or equivalently as a complex-valued discrete Fourier transform.
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Abstract
The present invention comprises a method and system for accurate estimation of the ion cyclotron resonance (ICR) parameters in Fourier-transform mass spectrometry (FTMS/FT-ICR MS). The parameters are essential to estimating the mass to charge ratio of an ion from FT-ICR MS data, the intended purpose of the instrument. Achieving greater accuracy in the parameters assists in greater accuracy of the mass to charge ratio of an ion, and obtaining an accurate estimation of the mass to charge ratio of an ion further aides in detecting mass with sub-ppm accuracy. Estimating mass in this manner enhances identification and characterization of large molecules. The inventive method and system thereby enhances the data obtained by conventional FTMS by accurately estimating ICR parameters. Ultimately, accurate estimates of the masses of molecules and detection and characterization of molecules from FT-ICR MS data are obtained.
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Citations
16 Claims
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1. A method for accurately estimating Fourier Transform mass spectrometry signal parameters comprising:
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(i) obtaining a time-series of voltage or current measurements of the time-dependent image charge generated upon two or more detector plates by whose motion inside an analyzer is essentially sinusoidal in one or more component directions; (ii) taking a discrete Fourier transform of the obtained time-series to produce a spectrum; and (iii) constructing maximum-likelihood estimates of a) frequency (f0), b) amplitude |α
|, c) phase (arg(α
)), and d) decay time constant (τ
) Fourier Transform mass spectrometry signal parameters from the acquired Fourier Transform mass spectrometry data using as a time-domain model an exponentially decaying sinusoid that has been truncated white Gaussian noise or its equivalent representation as a complex-valued discrete Fourier transform,wherein the Fourier Transform mass spectrometry data is represented either as a time-series of measurements or equivalently as a complex-valued discrete Fourier transform. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9-12. -12. (canceled)
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13. A computer readable medium having computer executable components for estimating Fourier Transform mass spectrometry parameters comprising
(i) obtaining a time-series of voltage or current measurements of the time-dependent image charge generated upon two or more detector plates by ions whose motion inside an analyzer is essentially sinusoidal in one or more component directions; -
(ii) taking a discrete Fourier transform of the obtained time-series to produce a spectrum; and (iii) constructing maximum-likelihood estimates of a) frequency (f0), b) amplitude |α
|, c) phase (arg(α
)), and d) decay time constant (τ
) Fourier Transform mass spectrometry signal parameters from the acquired Fourier Transform mass spectrometry data using as a time-domain model an exponentially decaying sinusoid that has been truncated to zero at the end of a finite acquisition interval of known duration plus additive white Gaussian noise or its equivalent representation as a complex-valued discrete Fourier transform,wherein the Fourier Transform mass spectrometry data is represented either as a time-series of measurements or equivalently as a complex-valued discrete Fourier transform. - View Dependent Claims (14)
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15. A Fourier Transform mass spectrometry machine comprising computer readable media having computer executable instructions for estimating Fourier Transform mass spectrometry parameters wherein the computer readable medium having computer executable instructions for estimating parameters on the Fourier Transform mass spectrometry machine comprises
((i) obtaining a time-series of voltage or current measurements of the time-dependent image charge generated upon two or more detector plates ions whose motion inside an analyzer is essentially sinusoidal in one or more component directions; -
(ii) taking a discrete Fourier transform of the obtained time-series to produce a spectrum; and (iii) constructing maximum-likelihood estimates of a) frequency (f0), b) amplitude |a|, c) phase (arg(a)), and d) decay time constant (τ
) Fourier Transform mass spectrometry signal parameters from the acquired Fourier Transform mass spectrometry data using as a time-domain model an exponentially decaying sinusoid that has been truncated to zero at the end of a finite acquisition interval of known duration plus additive white Gaussian noise or its equivalent representation as a complex-valued discrete Fourier transform,wherein the Fourier Transform mass spectrometry data is represented either as a time-series of measurements or equivalently as a complex-valued discrete Fourier transform. - View Dependent Claims (16)
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Specification