Ion Oscillation Signal Reconstruction for Accurate Charge Analysis
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Solution Overview
Problem
Current ion trap mass spectrometry methods face challenges in accurately measuring the charge of ions, particularly for highly charged biological ions, due to noise interference and spectral overlap, leading to errors in charge determination and reduced signal-to-noise ratios.
Innovation Solution
The method involves reconstructing a time-domain image-charge/current signal based on selected frequency-domain harmonic components of a truncated signal, which is synchronized with the oscillation period of the target ion, reducing spectral leakage and noise interference, and calculating the ion's charge from the reconstructed signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Fourier transformation is used to analyze image-charge/current signals, then mass spectrum data can be obtained, but spectral overlap and noise interference occur leading to reduced measurement precision
Solution Approach 1:
The patent segments the continuous image-charge/current signal into discrete oscillation cycles corresponding to individual ion oscillations. By identifying and isolating specific oscillation periods, the method separates the target ion signal from background noise and other interfering signals, thereby improving charge measurement accuracy without losing critical signal information.
Solution Approach 2:
The patent exploits the periodic nature of ion oscillations in the ion trap by analyzing the signal at specific oscillation periods. By synchronizing the analysis window with the ion's oscillation period, the method enhances the periodic signal components while suppressing aperiodic noise, thus improving the signal-to-noise ratio and measurement precision.
2Measurement precision
If traditional signal analysis methods are used, then processing is simpler, but charge determination errors increase due to noise interference
Solution Approach 1:
The patent performs preliminary signal processing by pre-identifying oscillation periods and selecting relevant signal segments before final charge determination. This preliminary action of filtering and organizing the signal data reduces noise interference early in the process, improving charge determination accuracy while keeping the overall methodology accessible to practitioners.
3Measurement precision
If the entire signal is analyzed, then more data is available, but spectral leakage occurs reducing measurement accuracy
Solution Approach 1:
The patent divides the entire signal into smaller segments corresponding to individual or grouped oscillation cycles. This segmentation prevents spectral leakage by ensuring each segment contains complete oscillation periods, allowing spectral energy to concentrate properly in the frequency domain while maintaining measurement precision through selective analysis of relevant segments.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves the accuracy of charge measurement by concentrating spectral energy within fewer frequency bins, reducing noise influence, and enhancing the signal-to-noise ratio, thereby providing more precise determination of ion charge.
Implementation Method 1
one or more ions undergoing oscillatory motion within an ion analyser apparatus (e.g. an ion trap) may induce an image-charge/current signal detectable by sensor electrodes of the apparatus configured for this purpose
Implementation Method 2
If ions are trapped using an electrostatic field, the ion trap mass spectrometer is commonly referred to as an 'electrostatic' ion trap mass spectrometer
Data Source
AI summary
A method of processing an image-charge/current signal representative of one or more ions undergoing oscillatory motion within an ion analyser apparatus. The method comprising obtaining a recording of the image-charge/current signal generated by the ion analyser apparatus in the time domain. By a signal processing unit, the method comprises determining a value for the period of a periodic signal component within the recorded signal. Then, the method includes truncating the recorded signal to provide a truncated signal having a duration substantially equal to an integer multiple of said period. A step of reconstructing a time-domain signal is done based on a selected one or more frequency-domain harmonic components of the truncated signal. Next, the method determines a magnitude of the reconstructed time-domain signal and therewith calculating a value representative of the charge of a said ion undergoing oscillatory motion within the ion analyser apparatus.