Image Current Mass Analyzer Calibration for Space Charge Accuracy
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Solution Overview
Problem
Image current-based mass analyzers in mass spectrometers face challenges in accurately determining the total number of ions injected due to space charge effects, chemical noise, ion transfer inefficiencies, and spray instability, which affect mass accuracy and precision.
Innovation Solution
A calibration management system uses an electron multiplier-based mass analyzer to determine a mass spectrum and ion counts, allowing for the setting of a calibration parameter for the image current-based mass analyzer based on total ion counts, accounting for chemical noise and transfer inefficiencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an image current-based mass analyzer is used to perform mass analysis, then mass analysis capability is provided, but mass accuracy and precision deteriorate due to space charge effects, chemical noise, ion transfer inefficiencies, and spray instability
Solution Approach 1:
The patent introduces an electron multiplier-based mass analyzer as an intermediary device to measure ion population characteristics before the ions enter the image current-based mass analyzer. This intermediary measurement system allows for determination of total ion count and calibration parameter adjustment, thereby compensating for the harmful space charge effects that would otherwise degrade mass accuracy in the main analyzer.
2Measurement precision
If an image current-based mass analyzer is used to perform mass analysis, then mass analysis capability is provided, but mass accuracy and precision deteriorate due to chemical noise, ion transfer inefficiencies, and spray instability
Solution Approach 1:
The patent performs preliminary measurement of ion population characteristics using the electron multiplier-based mass analyzer before the actual mass analysis in the image current-based mass analyzer. By measuring total ion count and calibration parameters in advance, the system can adjust injection parameters and compensate for ion transfer inefficiencies and spray instability, thereby maintaining mass precision despite these reliability issues.
3Measurement precision
If total ion count is determined accurately, then calibration accuracy is improved, but measurement complexity increases due to need for separate ion count measurement system
Solution Approach 1:
The patent employs an electron multiplier-based mass analyzer that serves multiple functions: it performs initial mass analysis to determine total ion count, measures calibration parameters, and characterizes ion population distribution. This multi-functional approach enables accurate calibration without requiring entirely separate measurement systems, thereby limiting the increase in device complexity while achieving high calibration accuracy.
Data Source
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AI summary
An illustrative method comprises determining, based on a mass analysis performed by an electron multiplier-based mass analyzer on a first ion population produced from a sample, a mass spectrum comprising one or more peaks representing intensity as a function of mass-to-charge ratio (m/z) of the first ion population across a range of m/z values; determining, based on the mass spectrum, a total ion count of the first ion population and a peak ion count associated with a peak located at a particular m/z value; determining, based on the total ion count of the first ion population and the peak ion count, a total ion count of a second ion population produced from the sample and injected into an image current-based mass analyzer for mass analysis; and setting, based on the total ion count of the second ion population, a calibration parameter for the image current-based mass analyzer.