Mass Spectrometry Data Acquisition Using Discontinuous Ion Channels
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Solution Overview
Problem
Current mass spectrometry data acquisition methods face challenges in achieving high ion duty cycle and quantitative analysis using ion current chromatograms of product ions, particularly in omics research, where many precursor ions with low abundance are not monitored, and selectivity and precision are reduced due to non-uniform detection of product ions during chromatographic elution.
Innovation Solution
A data acquisition method for mass spectrometry that involves generating ions, recording mass spectra in both low and high fragmenting modes, selecting ions across discontinuous mass-to-charge ratio channels, and repeatedly fragmenting and recording spectra until ion intensity drops below a threshold, allowing for uniform detection and association of ions with chromatographic peaks for quantitative analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If data-dependent acquisition scheme is used to increase coverage of polypeptides, then more precursor ions can be monitored, but the duty cycle and throughput are low because only one product ion scan can be performed per precursor ion
Solution Approach 1:
The invention divides the mass-to-charge ratio range into multiple discrete channels, allowing simultaneous monitoring of multiple precursor ions across different channels. This segmentation enables parallel acquisition of product ion scans for multiple precursors, thereby increasing throughput and duty cycle while maintaining comprehensive coverage.
Solution Approach 2:
The mass spectrometer system is configured to perform multiple functions simultaneously: it can conduct precursor ion scans, product ion scans, and quantitative analysis across multiple mass-to-charge ratio channels in parallel. This multi-functionality resolves the contradiction by enabling the system to monitor many precursor ions without sacrificing duty cycle.
2Quantity of substance
If mass-to-charge ratio channels change constantly in each cycle to monitor different precursor ions, then coverage is improved, but uniform detection of product ions for quantitative analysis cannot be ensured
Solution Approach 1:
The invention performs preliminary scanning to identify precursor ions and their corresponding product ions before quantitative analysis. This preliminary action establishes a fixed mapping between precursor ions and product ions, which is then used for consistent monitoring throughout the analysis. This ensures that the same product ion channels are repeatedly monitored for the same precursors, enabling uniform detection and accurate quantitative analysis.
Solution Approach 2:
The system uses feedback from preliminary scans and real-time monitoring to maintain consistent mass-to-charge ratio channel assignments for quantitative analysis. By continuously monitoring the same product ion channels for identified precursors, the system ensures uniform detection across chromatographic elution, resolving the contradiction between coverage and measurement precision.
3Quantity of substance
If many precursor ions with low abundance are monitored, then coverage is improved, but selectivity and precision of quantitative analysis are reduced
Solution Approach 1:
The invention applies different quality levels to different mass-to-charge ratio channels based on precursor ion abundance. High-abundance precursors receive enhanced monitoring with repeated product ion scans for quantitative analysis, while low-abundance precursors are monitored with appropriate sensitivity. This local quality differentiation maintains selectivity and precision for quantitative analysis while preserving coverage of low-abundance ions.
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 method enhances ion duty cycle and quantitative accuracy by ensuring uniform detection of product ions across chromatographic elution, improving selectivity and precision in tandem mass spectrometry analysis.
Implementation Method 1
a. providing at least one ion source for generating ions
Implementation Method 2
e. fragmenting at least part of the selected ions distributed in the discontinuous mass-to-charge ratio channels when the collision cell is in a second working mode
Data Source
AI summary
A data acquisition method for a mass spectrometer includes providing at least one ion source for generating ions; not fragmenting or less fragmenting the ions when a collision cell is in a first working mode; recording a mass spectrum of the ions generated in the first working mode; selecting more than one ion from the ions, the more than one ion being distributed in a plurality of discontinuous mass-to-charge ratio channels; partially fragmenting the selected ions when the collision cell is in a second working mode; recording a mass spectrum of the ions generated in the second working mode; and, repetitively executing the above steps for several times. The ions distributed in the discontinuous mass-to-charge ratio channels is always selected during the subsequent repeated execution, until the ion intensity of the selected ions is less than a set value.