TOF Mass Spectrometer Gain Control for Dynamic Range
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Solution Overview
Problem
Conventional Time-of-Flight Mass Spectrometry (TOF-MS) faces challenges in achieving high measurement accuracy due to insufficient dynamic range in A/D converters, leading to signal reproducibility issues and increased measurement time, especially when dealing with varying ion signal levels over time.
Innovation Solution
Implementing a mass spectrometer with amplitude value computing means to determine optimal gain settings for each TOF scan, using an A/D converter with gain control to adjust the ion detection signal, and providing a new detector to measure ion amounts, ensuring high dynamic range and preventing overrange occurrences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gain switching means is provided and remeasurement is performed for overrange detection, then measurement accuracy is improved, but measurement time is increased
Solution Approach 1:
The patent applies preliminary action by performing a test measurement before the actual mass spectrum measurement to determine the appropriate gain setting. This preliminary gain determination prevents overrange during the main measurement, eliminating the need for remeasurement and thus reducing total measurement time while maintaining accuracy.
Solution Approach 2:
The patent implements dynamic gain adjustment by automatically selecting different gain settings based on the ion signal level detected during test measurement. This dynamic adaptation allows the system to optimize measurement parameters in real-time, improving accuracy without requiring multiple fixed measurements.
2Measurement precision
If multiple TOF scans are added to increase measurement sensitivity, then signal-to-noise ratio is improved, but measurement time is increased
Solution Approach 1:
The patent performs a preliminary TOF scan before the actual mass spectrum measurement to determine the ion signal level. This preliminary scan allows the system to set the optimal gain before accumulating multiple scans, ensuring that all subsequent scans are performed at the optimal sensitivity setting without requiring additional scans for gain optimization.
Solution Approach 2:
The system dynamically adjusts the gain setting based on the ion signal level detected during the preliminary scan. This dynamic adjustment ensures that multiple scans are accumulated at the optimal gain setting from the start, maximizing signal-to-noise ratio without requiring extra scans for optimization.
3Device complexity
If fixed gain settings are used in the gain adjuster, then device complexity is reduced, but measurement accuracy deteriorates when ion signal levels vary
Solution Approach 1:
The patent introduces a preliminary measurement step that determines the appropriate gain setting before the actual mass spectrum measurement. This simple addition to the fixed gain system allows automatic adaptation to varying ion signal levels without requiring complex real-time gain adjustment mechanisms during the main measurement.
Solution Approach 2:
The system performs self-service by automatically determining the optimal gain setting through preliminary measurement and then using this information to configure the gain adjuster for the main measurement. This self-configuration eliminates the need for manual gain setting and allows the system to adapt to different sample conditions automatically.
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 allows for efficient acquisition of high-reproducibility mass spectra with high dynamic range, reducing measurement time and maintaining accuracy even when ion signal levels vary, by dynamically adjusting gain settings based on real-time ion concentration.
Implementation Method 1
a data acquisition circuit using an A/D converter, and data of the ion detection signal is outputted
Implementation Method 2
When ions reach (collide with) a detector in the TOF region, an ion detection signal is outputted from the detector
Implementation Method 3
a Time-Of-Flight (TOF) region, the ionized sample is accelerated and allowed to fly, and a time of flight depending on its mass
Data Source
AI summary
The present invention relates to a data processing device for mass spectrometry, in which measurements are performed in a high dynamic range without causing an overrange in an A/D converter in any TOF scan. A data acquisition circuit of a mass spectrometer includes an amplitude value computing circuit which measures and stores a maximum amplitude value of an ion detection signal, a gain control circuit for determining and setting a gain amount for the next measurement, and others. From the immediately preceding TOF scan data or TOF scan data plural times before, the maximum amplitude value of the ion detection signal is extracted. Then, before the next TOF scan, an optimum gain amount is determined based on the extracted maximum amplitude value to adjust the gain of the input signal, and the ion signal is sampled in the A/D converter.