Information-Dependent Acquisition Triggering for Mass Spectrometry
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Solution Overview
Problem
Identifying species of interest in complex mixtures using coupled mass spectrometry systems is challenging due to overlapping ion signals and false positive triggers in real-time analysis, especially in biological fluids or protein digests, where conventional data acquisition software struggles to select the correct precursor ions for MS/MS analysis.
Innovation Solution
Implementing an information-dependent acquisition (IDA) system that combines ion signal characteristics of multiple reaction monitoring (MRM) transitions to create a selection criterion for triggering dependent mass spectrometry scans, ensuring that all ion signal characteristics meet predetermined thresholds or criteria before initiating a scan, thereby reducing false positives and focusing on the compound of interest.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If conventional data acquisition software is used to identify species of interest in real-time, then the system can perform automated MS/MS analysis, but false positive triggers occur due to overlapping ion signals from complex mixtures
Solution Approach 1:
The patent combines multiple ion signal characteristics (intensity, mass-to-charge ratio, temporal profile) from multiple MRM transitions into a unified selection criterion. This merging of multiple parameters allows the system to distinguish true species signals from background noise and overlapping signals, thereby maintaining automated identification while reducing false positive triggers in complex mixtures
Solution Approach 2:
The system changes the parameters used for species identification by evaluating multiple ion signal characteristics simultaneously rather than relying on a single parameter. By implementing a multi-parameter selection criterion that includes intensity thresholds, mass-to-charge ratio matching, and temporal signal profiles, the system improves reliability while maintaining automation capability
2Speed
If dependent mass spectrometry scans are triggered based on single ion signal detection, then the system responds quickly to eluting species, but redundant data is generated from incorrect precursor ion selection
Solution Approach 1:
The patent implements preliminary evaluation of ion signal characteristics against predefined selection criteria before triggering dependent scans. By pre-establishing criteria based on multiple MRM transition characteristics and evaluating signals against these criteria in advance, the system maintains rapid real-time response while preventing redundant scans from incorrect precursor ion selection, thus reducing information loss
3Measurement precision
If multiple MRM transitions are monitored to improve species identification accuracy, then the system can distinguish compounds better, but the complexity of data acquisition increases
Solution Approach 1:
The patent segments the complex data acquisition process into distinct evaluation steps: monitoring multiple MRM transitions, evaluating each transition's ion signal characteristics against selection criteria, and triggering scans only when criteria are met. This segmentation of the acquisition process into manageable stages improves measurement precision through multiple transition monitoring while managing complexity through structured, stepwise evaluation
Data Source
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AI summary
Methods and systems are provided for triggering an information dependent mass spectrometry scan in real time. A mass spectrometry scan of a separating sample mixture is performed by a mass spectrometer at each time interval of a time period. The mass spectrometer receives the separating sample mixture from a separation device. It is determined at a certain time interval that a received mass spectrometry scan at the time interval and one or more preceding received mass spectrometry scans include two or more time-varying ion signals that represent two or more fragment ion transitions of a known compound. If a characteristic of the two or more time-varying ion signals meets a selection criterion, the mass spectrometer is instructed to perform a dependent mass spectrometry scan of the separating sample mixture for a precursor ion of the known compound at the time interval.