Mass Spectrometer Gain Control Using Stored Ion Current Signals
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Solution Overview
Problem
Mass spectrometers face limitations in dynamic range, particularly due to space charge effects and ion saturation, which affect the accuracy of ion current estimation and automatic gain control, especially when dealing with varying sample amounts and types.
Innovation Solution
A method that estimates ion current by selecting signals from stored data based on operating parameters, allowing for optimal automatic gain control strategies across different analytical instruments, including mass spectrometers and ion detectors, to prevent space charge effects and saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pre-scan is performed to measure ion current for automatic gain control, then the accuracy of ion current estimation is improved, but the analysis time is increased due to the additional measurement step
Solution Approach 1:
The patent performs a pre-scan measurement of ion current before the actual analytical measurement. This preliminary action allows the system to estimate the ion current that will be present during the main analysis, enabling automatic gain control to be configured optimally. The pre-scan is performed quickly and the ion current estimation is used to set the accumulation time for the subsequent analytical measurement, thus improving measurement precision without significantly impacting overall analysis time.
2Measurement precision
If the accumulation time is increased to obtain sufficient ions for analysis, then the quality of mass spectra is improved, but the rate at which different analytes can be studied is reduced due to space charge effects
Solution Approach 1:
The patent implements automatic gain control that uses feedback from the measured ion current to adjust the accumulation time dynamically. The system measures the ion current (either via pre-scan or during the analysis) and uses this information to calculate the optimal accumulation time required to achieve a target number of ions. This feedback mechanism ensures that sufficient ions are accumulated for high-quality mass spectra while avoiding excessive accumulation times that would cause space charge effects and reduce the analysis rate of different analytes.
Solution Approach 2:
The patent makes the accumulation time dynamic rather than fixed. The accumulation time is adjusted in real-time based on the measured ion current and the desired target ion count. This dynamic adjustment allows the system to optimize the accumulation time for each analytical measurement, ensuring high-quality spectra are obtained while maintaining high productivity by avoiding unnecessarily long accumulation times that would trigger space charge effects.
3Productivity
If the accumulation time is decreased to increase the analyte analysis rate, then the productivity is improved, but the mass spectra quality deteriorates due to insufficient ion accumulation
Solution Approach 1:
The automatic gain control system continuously monitors the ion current and uses this feedback to calculate the precise accumulation time needed to reach the target ion count. This ensures that even when accumulation times are shortened to increase productivity, sufficient ions are still accumulated to maintain high mass spectra quality. The feedback mechanism prevents under-accumulation by adjusting the accumulation time based on real-time ion current measurements.
4Device complexity
If a single automatic gain control method is implemented on a single instrument, then the device complexity is minimized, but the adaptability to different instruments and methods is reduced
Solution Approach 1:
The patent implements a universal automatic gain control system that can be applied across different analytical instruments and measurement methods. The core principle of measuring ion current and using it to control accumulation time is instrument-agnostic and can be adapted to various mass spectrometry instruments and techniques. This universal approach allows the same fundamental AGC methodology to be implemented on different instruments without requiring instrument-specific complex control algorithms, thus maintaining low device complexity while achieving high adaptability.
Data Source
AI summary
A first analytical instrument is configured to be controlled according to one or more first operating parameters; and controlling the configured first analytical instrument based on an estimated ion current obtained by: selecting at least one signal from stored data comprising a plurality of signals and a respective one or more second operating parameters associated with each of the plurality of signals, wherein each signal of the plurality of signals is representative of an ion current obtained using the first analytical instrument configured according to the respective associated one or more second operating parameters or using a second analytical instrument configured according to the respective associated one or more second operating parameters, and wherein the at least one signal is selected based on the one or more first operating parameters; and using the at least one selected signal to estimate the ion current.