Mass Spectrometry Ion Population Control Using XIC Prediction
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Solution Overview
Problem
Conventional Automated Gain Control (AGC) methods in mass spectrometry fail to accurately regulate ion population due to assumptions of constant ion flux, leading to overshooting or undershooting the target number of ions, especially during dynamic and non-Gaussian ion flux changes in LC-MS or GC-MS analyses, which degrades analytical performance.
Innovation Solution
A method involving the determination of a predicted next detection point in an elution profile using a series of mass spectra, where a machine learning model is trained to predict the next detection point based on historic intensity values, allowing for accurate setting of accumulation times to prevent ion overfilling or underfilling, and enabling data-dependent acquisitions at optimal times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional AGC methods use prior acquisition ion flux estimates to set accumulation time, then the system operates with simple control logic, but the ion population regulation accuracy deteriorates due to rapidly changing ion flux during LC-MS or GC-MS analyses
Solution Approach 1:
The system performs preliminary actions by acquiring multiple prescan mass spectra before the actual scan to estimate future ion flux. This allows the accumulation time to be set based on predicted rather than historical ion flux, preventing overshooting or undershooting of target ion population while maintaining manageable control logic.
Solution Approach 2:
The system implements feedback by continuously monitoring ion flux through prescan acquisitions and using this information to dynamically adjust accumulation time for subsequent scans. This closed-loop approach ensures accurate ion population regulation even when ion flux changes rapidly during chromatographic analysis.
2Reliability
If the accumulation time is increased to capture sufficient ions during low ion flux periods, then ion detection sensitivity improves, but analytical throughput deteriorates due to longer scan times
Solution Approach 1:
The system dynamically adjusts accumulation time based on real-time ion flux conditions estimated from prescan data. During low ion flux periods, accumulation time is extended to ensure sufficient ion population for sensitive detection. During high ion flux periods, accumulation time is reduced to maintain analytical throughput, optimizing both sensitivity and productivity across varying conditions.
Solution Approach 2:
The system changes the accumulation time parameter adaptively based on estimated ion flux from prescan acquisitions. This allows the system to optimize ion population for each scan based on actual conditions rather than using a fixed accumulation time, thereby maintaining both sensitivity and throughput.
3Measurement precision
If multiple prescans are performed to improve ion flux estimation accuracy, then ion population regulation improves, but time for analytical scans deteriorates as prescan time cannot be used for data acquisition
Solution Approach 1:
The system performs a limited number of prescan acquisitions (e.g., 1-3 prescans) rather than extensive sampling, providing sufficient ion flux estimation accuracy without excessive time consumption. This partial action approach balances the need for accurate regulation with the need to maximize analytical scan time.
Solution Approach 2:
The system maintains continuity of useful action by performing prescan acquisitions that immediately inform the setup of subsequent analytical scans. The prescan data is used without delay to optimize accumulation time, ensuring that the transition from estimation to data acquisition is seamless and minimizes idle time.
Data Source
AI summary
A method of performing mass spectrometry includes obtaining, based on a series of mass spectra of detected ions derived from components eluting from a chromatography column, a plurality of extracted ion chromatograms (XICs), each XIC comprising a plurality of detection points representing detected intensity for a distinct selected m/z as a function of time; detecting, based on the series of mass spectra, precursor ions of each distinct selected m/z of the plurality of XICs; and determining, for each XIC based on a set of detection points of the XIC, a predicted next detection point to be obtained based on a next mass spectrum to be acquired.