Mass Spectrometer Calibration with Ion-Specific Detector Gain
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Solution Overview
Problem
Mass spectrometers face reduced detector wear and sensitivity limitations due to high ion production rates during calibration and tuning, leading to decreased electron multiplier lifetime.
Innovation Solution
A method and system for operating a mass spectrometer that involves reducing the emission current during detector gain calibration, allowing single ion events to dominate the signal and Poisson statistics to control root mean square deviation, and adjusting the electron beam and detector gain to optimize ion production and detection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of ions produced per unit time is increased to improve sensitivity and detection limits, then the detection capability is improved, but the electron multiplier lifetime is reduced due to increased detector wear
Solution Approach 1:
The patent applies parameter changes by adjusting the detector gain to an ion-specific gain value during calibration based on the expected ion abundance for each calibrant ion. This allows optimal detection sensitivity for each ion type while avoiding excessive ion production that would wear the detector. The system dynamically changes the gain parameter rather than maintaining a fixed high gain setting, thereby preserving detector lifetime while maintaining detection capability.
2Manufacturing precision
If high ion production rate is used during calibration and tuning, then calibration accuracy is improved, but detector wear increases leading to reduced operational lifetime
Solution Approach 1:
The system changes the detector gain parameter dynamically during calibration based on the specific ion being calibrated. By setting ion-specific gain values rather than using high gain for all ions, the system achieves accurate calibration for each ion type while reducing the overall ion production rate and associated detector wear.
Solution Approach 2:
The patent applies partial action by producing ions at a moderate rate and compensating with ion-specific gain settings. Rather than producing excessive ions for all calibrations and relying on uniform high gain, the system uses targeted, moderate ion production combined with optimized gain values for each ion type, achieving accurate calibration with reduced detector stress.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach extends detector lifetime and improves sensitivity by reducing ion production during calibration and tuning, maintaining optimal signal intensity and reducing wear on the detector.
Implementation Method 1
the electron emitter can be a thermionic filament or a field emitter
Implementation Method 2
the electron emitter can be a thermionic filament or a field emitter
Implementation Method 3
accelerating electrons from an electron emitter through the ionization chamber along a source axis
Implementation Method 4
high abundance ions and low abundance ions can be produced by ionizing a calibration mixture including one or more calibrant species
Implementation Method 5
reducing the emission current during detector gain calibration, allowing single ion events to dominate the signal
Data Source
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AI summary
A method of operating a mass spectrometer comprising: detecting a first ion species using a first gain setting of a detector or a first emission current for a first mass-to-charge range; detecting a second ion species using a second gain setting of the detector or a second emission current for a second mass-to-charge range; and using the detected first and second ion species to calibrate the mass range of a mass analyzer of the mass spectrometer, to tune the resolution of the mass analyzer, or to tune an ion optic of the mass spectrometer.