Ion Charge-State Analysis Using Integer Frequency Matching
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Solution Overview
Problem
Existing ion analysis methods face challenges in accurately determining the charge of ions due to assumptions about ion clouds and the impact of space charges, leading to reduced accuracy in mass measurement, especially for large ions and in the presence of noise.
Innovation Solution
A method that processes image-charge/current signals by rounding estimated charge values to integers, scoring candidate charge values based on similarity with measured signal frequencies, and using a scoring system to determine the accurate charge state of ions, without the need for complex electronics or cryogenic cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard Fourier transformation methods are used to analyze image-charge/current signals, then the analysis process is simple and fast, but the accuracy of charge determination is reduced due to noise and space charge effects
Solution Approach 1:
The patent applies preliminary action by performing integer rounding of charge values before further analysis. This pre-processing step eliminates fractional charge values that arise from noise, establishing a foundation for more accurate subsequent frequency matching and charge state determination.
Solution Approach 2:
The patent implements feedback through an iterative scoring system where candidate charge values are evaluated based on how well their predicted frequencies match observed signal frequencies. The scoring mechanism provides feedback that guides the selection of the most accurate charge determination, continuously refining the result through comparison and validation.
2Measurement precision
If assumptions about uniform charge distribution in ion clouds are made, then the analysis is simplified, but accuracy is reduced especially for large ions and multiply charged ions
Solution Approach 1:
The patent applies preliminary action by performing integer rounding of charge values before further analysis. This pre-processing step eliminates fractional charge values that arise from noise, establishing a foundation for more accurate subsequent frequency matching and charge state determination.
Solution Approach 2:
The patent changes the parameter representation by working with integer charge values rather than continuous floating-point values. This parameter transformation discretizes the charge space, making the analysis more robust to noise and space charge effects while improving the accuracy of mass measurements for large and multiply charged ions.
3Measurement precision
If complex electronics or cryogenic cooling are used to improve signal detection, then measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces complex mechanical and physical systems (cryogenic cooling equipment, complex electronics) with a computational data processing method. By using integer rounding and frequency matching algorithms, the invention achieves improved signal detection accuracy through software-based processing rather than hardware-based physical modifications.
Solution Approach 2:
The patent employs simple, computationally inexpensive processing steps (integer rounding, frequency comparison) that can be executed rapidly without requiring expensive, complex, or fragile equipment. This approach achieves high measurement accuracy using accessible computational resources rather than sophisticated hardware infrastructure.
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 ion charge measurement, leading to higher accuracy mass spectra by accurately determining the charge state of ions and reducing misassignments, thus enhancing the precision of mass spectrometry without requiring expensive equipment.
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
The most popular transformation for this purpose is the Fourier transformation (FT). Fourier transformations decompose a time-domain signal into sinusoidal components, each component having a specific frequency (or period), amplitude and phase.
Data Source
AI summary
A method of processing data determined from an image-charge/current signal representative of ions of a given charge state (Q) undergoing oscillatory motion of a respective oscillation frequency (f) within an ion analyser apparatus. A data set comprises a measured signal frequency (f0) common to a plurality of a measured image-charge/current signals and a plurality of estimated ion charge values corresponding to respective amplitudes of each one of the plurality of measured image-charge/current signals. An integer charge value ([Q]) is generated corresponding to a said estimated ion charge value rounded to the nearest integer value. Using the integer charge value ([Qi]) a plurality of different candidate image-charge/current signal frequency values (fCandi) are calculating according to said selected measured signal frequency (f0) and according to a corresponding one of one or more different candidate charge states of ion (e.g., protonation) and/or of ion isotope or isotopologue. The calculated plurality of different candidate image-charge/current signal frequency values (fCandi) are compared to a plurality of different signal frequencies (f) of the measured image-charge/current signals and a score value is calculated representing a degree of similarity therebetween according to the comparison. The charge state (Q) of the ion undergoing oscillatory motion of said selected measured signal frequency (f0), is then determined to be equal to the integer charge value ([{circumflex over (Q)}l,]) if the score value matches or exceeds a threshold score value.