Ion Signal Harmonic Correction for Accurate Charge Analysis
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Solution Overview
Problem
Current ion trap mass spectrometry methods face challenges in accurately determining the charge of ions, especially for highly charged biological ions, due to noise interference and spectral overlap, leading to measurement errors and reduced signal-to-noise ratios.
Innovation Solution
The method involves processing image-charge/current signals by selecting specific frequency-domain harmonic components, correcting for spectral interferences, and using a system of equations to isolate the target ion's charge, thereby improving the accuracy of charge measurement and reducing noise influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Fourier transformation is used to analyze image-charge/current signals from multiple ions, then mass spectrum data can be obtained, but spectral overlap between different ions causes measurement errors in charge determination
Solution Approach 1:
The patent segments the image-charge/current signal into multiple time segments and applies Fourier transformation to each segment separately. This time-domain segmentation allows resolution of spectral overlaps by analyzing ions at different time intervals, thereby improving charge determination accuracy while maintaining mass spectrum information.
Solution Approach 2:
The patent introduces a time dimension by analyzing signals in both time and frequency domains. By segmenting the time domain and applying Fourier transformation, the method creates a three-dimensional analysis space (time segments × frequency components × ion identities), enabling separation of overlapping spectral information that cannot be resolved in traditional two-dimensional frequency domain analysis.
2Productivity
If multiple ions are trapped simultaneously for analysis, then throughput is improved, but noise interference and spectral overlap increase
Solution Approach 1:
The patent divides the continuous signal from multiple simultaneously trapped ions into discrete time segments. Each segment is processed independently through Fourier transformation, allowing the system to maintain high throughput by analyzing multiple ions concurrently while reducing noise interference through temporal separation and selective frequency analysis of each segment.
3Measurement precision
If traditional Fourier transformation is applied to the entire signal, then complete mass spectrum is obtained, but signal-to-noise ratio decreases due to interference from all ions
Solution Approach 1:
The patent segments the total ion signal into multiple time-based portions and applies Fourier transformation to each segment individually. This approach maintains the complete mass spectrum information across all segments while improving signal-to-noise ratio by analyzing smaller time windows where fewer ions are present, thereby reducing cumulative interference.
Solution Approach 2:
Instead of transforming the entire signal at once, the patent applies partial Fourier transformations to specific time segments. This partial action on subsets of the total signal allows selective enhancement of signal-to-noise ratio for specific ion populations while preserving the ability to reconstruct the complete mass spectrum from all 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 enhances the accuracy of ion charge determination by isolating the target ion's spectral energy and reducing interference from other ions, resulting in improved signal-to-noise ratios and more precise charge measurements.
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
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
Implementation Method 3
the frequency of oscillation of trapped ions in an ion trap mass spectrometer is dependent on the mass-to-charge (m/z) ratio of the ions
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 includes selecting N (where N is an integer>1) separate values (OPn, where n=1 to N; N≥M) of the frequency-domain spectrum of the image-charge/current signal each from amongst a plurality of spectral peaks which include a harmonic peak associated with a target ion. By solving a system of equations:OPn=∑m=1Nαnm×TPm,for n=1 to N;N≥Mwhere αnm are coefficients and TPm are corrected values of the spectrum, the charge of the target ion is determined based on a magnitude of a corrected value(s) (TPm) associated with that ion.