Predictive Automatic Gain Control for Hybrid Mass Spectrometers
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Solution Overview
Problem
Existing automatic gain control methods for mass spectrometers are inaccurate when used in hybrid instruments with significantly different isolation efficiencies between mass analyzers, leading to incorrect ion flux predictions and accumulation times.
Innovation Solution
Characterizing and parameterizing ion transfer efficiencies across different mass spectrometer components allows for accurate prediction of ion flux by using intensity information from previous survey acquisitions, even when instrumental parameters change, and accounting for 'mass spectrometric dark matter' that contributes to charge density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional automatic gain control methods are used in hybrid mass spectrometers, then the instrument can operate with multiple mass analyzers, but the ion flux prediction becomes inaccurate due to different isolation efficiencies between analyzers
Solution Approach 1:
The patent introduces a correction factor that accounts for differences in isolation efficiency between mass analyzers. This correction factor is determined by comparing the actual ion flux measured in dependent scans with the ion flux predicted from survey scans, thereby adjusting the AGC calculation to maintain accuracy across different analyzer types
Solution Approach 2:
The patent uses an intermediary correction factor that bridges the discrepancy between survey scan data and dependent scan reality. This correction factor acts as a mediator that translates survey scan intensity information into accurate ion flux predictions for dependent scans, accounting for the different isolation efficiencies of hybrid analyzers
2Reliability
If ion accumulation time is extended to achieve optimal ion population, then the quality of MS/MS analysis improves, but the instrument scan rate decreases
Solution Approach 1:
The patent implements feedback by using actual ion flux measurements from dependent scans to refine the correction factor, which then improves future ion accumulation time predictions. This feedback loop enables the system to learn from actual performance and optimize accumulation times to achieve the best balance between analysis quality and scan rate
Solution Approach 2:
The patent performs preliminary characterization of the hybrid mass analyzer system to determine the correction factor before actual MS/MS analysis. This preliminary action enables accurate ion accumulation time prediction from the outset, eliminating the need for trial-and-error adjustments during analysis and maximizing both quality and productivity
Data Source
AI summary
A method for mass analyzing ions comprising a restricted range mass-to-charge (m/z) ratios comprising (i) performing a survey mass analysis, using a first mass analyzer employing indirect detection of ions by image current detection, to measure a flux of ions having m/z ratios within said range and (ii) performing a dependent mass analysis, using a second mass analyzer, of an optimal quantity of ions having m/z ratios within said range, said optimal quantity collected for a time period determined by the measured ion flux, the method characterized in that: the time period is determined using a corrected ion flux that includes a correction that comprises an estimate of the quantity of ions that are undetected by the first mass analyzer.