Real-Time Spectral Exclusion for Redundant MS2 Scan Avoidance
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Solution Overview
Problem
Existing data-dependent mass spectrometry methods face inefficiencies due to redundancies in MS2 analysis caused by selecting product ions that have already been analyzed, leading to wasted scans and skewed dataset confidence thresholds.
Innovation Solution
Implementing a real-time spectral search to dynamically exclude product ions by adding their mass-to-charge ratios to an exclusion list, based on theoretical fragments, mass accuracy, and resolution, using multiple mass analyzers with different resolutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If data-dependent MS2 analysis is performed on all detected ions, then comprehensive structural information can be obtained, but redundant analysis of product ions already present in the master scan increases analysis time and reduces productivity
Solution Approach 1:
The patent performs a preliminary search of the master scan spectrum to identify product ions before initiating MS2 analysis. By预先 checking whether product ions are already present in the master scan, the system avoids redundant MS2 scans and directs analysis only to precursor ions that will generate novel structural information, thus resolving the contradiction between comprehensive information gathering and analysis throughput
2Productivity
If dynamic exclusion lists are used to prevent redundant analysis, then analysis time is reduced, but the complexity of data management and decision-making increases
Solution Approach 1:
The patent establishes exclusion criteria based on preliminary inspection of the master scan spectrum. By pre-identifying product ions that would result in redundant analysis and adding them to an exclusion list before MS2 acquisition, the system simplifies real-time decision-making while maintaining high productivity, avoiding the need for complex dynamic adjustments during analysis
3Quantity of substance
If MS2 scans are performed on product ions present in the master scan, then data volume increases, but the confidence threshold for dataset identification becomes skewed and less reliable
Solution Approach 1:
The patent extracts and removes product ion signals from the master scan spectrum before using it for precursor ion selection. By taking out the contribution of product ions that would lead to redundant MS2 scans, the system maintains an accurate representation of true precursor ion abundances, ensuring that the confidence thresholds for dataset identification remain reliable and unbiased
Data Source
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Figure 3A~3B
AI summary
A method includes obtaining a first mass spectrum; selecting a first peak of the first mass spectrum; fragmenting and analyzing ions of the first peak to obtain a second mass spectrum; performing a real-time spectral search for compounds corresponding to peaks in the second mass spectrum; identifying fragments for the compounds identified based on the real-time spectral search; adding mass-to-charge ratios for the fragments to an exclusion list; selecting a second peak present in the first mass spectrum and not on the exclusion list; and fragmenting and analyzing ions of the second peak to obtain a third mass spectrum.