Time-of-Flight Mass Spectrometer Detector Voltage Auto-Tuning
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Solution Overview
Problem
In time-of-flight mass spectrometers using DC-type detectors, determining an appropriate detector voltage is challenging due to the influence of sample and device conditions, making it difficult to maintain sensitivity and dynamic range without affecting the detector's performance.
Innovation Solution
A time-of-flight mass spectrometer with a controller that adjusts the voltage to create a non-converging condition for ions, allowing the detector voltage to be determined based on peak characteristics in profile spectra, ensuring appropriate sensitivity and dynamic range without being affected by sample or device conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the detector voltage is increased to improve detection sensitivity for low-concentration components, then the signal intensity for low-concentration components is sufficiently obtained, but the signal intensity for high-concentration components reaches saturation level and the dynamic range becomes narrow
Solution Approach 1:
The patent applies dynamics by making the detector voltage adjustable and controllable based on sample concentration. The system dynamically changes the detector voltage according to the estimated concentration range of the sample, allowing optimal detection sensitivity for each specific measurement condition rather than using a fixed voltage setting.
Solution Approach 2:
The patent changes the detector voltage parameter according to the sample's concentration range. By estimating the concentration range first and then adjusting the detector voltage accordingly, the system optimizes the gain for different concentration levels, preventing both saturation of high-concentration signals and insufficient detection of low-concentration signals.
2Adaptability or versatility
If the detector voltage is decreased to extend the dynamic range for high-concentration components, then the signal intensity for high-concentration components does not reach saturation, but the detection sensitivity for low-concentration components becomes insufficient
Solution Approach 1:
The system dynamically adjusts the detector voltage based on the sample concentration. When measuring samples with wider concentration ranges, the voltage is optimized for each component's concentration level, ensuring that both high and low concentration components are detected within the linear range without saturation or insufficient sensitivity.
Solution Approach 2:
The detector voltage parameter is changed according to the specific measurement requirements. By estimating the concentration range and selecting appropriate voltage settings, the system adapts the detection parameters to match the sample characteristics, maintaining optimal performance across different concentration levels.
3Extent of automation
If the detector voltage is adjusted based on peak-intensity value to maintain constant sensitivity, then automatic adjustment is realized, but the peak-intensity value does not always reflect the exact number of ions and may be affected by sample and device conditions
Solution Approach 1:
The patent applies preliminary action by first estimating the concentration range of the sample before adjusting the detector voltage. This preliminary estimation allows the system to set appropriate voltage parameters in advance, avoiding the need to rely on peak-intensity feedback that may be inaccurate due to various interfering factors.
Solution Approach 2:
The patent introduces concentration range estimation as an intermediary step between sample introduction and detector voltage adjustment. This intermediary process provides more reliable information about the sample characteristics than peak-intensity values alone, enabling more accurate voltage optimization without being affected by device conditions or sample matrix effects.
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
Enables automatic determination of the detector voltage, ensuring consistent sensitivity and dynamic range, and alerts for detector deterioration, allowing for timely replacement.
Implementation Method 1
an ejector for imparting acceleration energy to ions originating from a sample component to eject the ions into a flight space
Implementation Method 2
a flight-space-forming electrode for creating, within the flight space, an electric field of a predetermined condition which makes the ions ejected by the ejector fly in the flight space
Implementation Method 3
a detector for detecting the ions after the ions' flight in the flight space
Data Source
AI summary
For an automatic adjustment of a detector voltage, a measurement of a standard sample is performed, in which a reflection voltage generator under the control of an autotuning controller applies, to a reflector, voltages which are different from those applied in a normal measurement and do not cause temporal conversion of ions. Ions having the same m/z simultaneously ejected from an ejector are dispersed in the temporal direction and reach a detector. Therefore, a plurality of low peaks corresponding to individual ions are observed on a profile spectrum. A peak-value data acquirer determines a wave-height value of each peak. A wave-height-value list creator creates a list of wave-height values. A detector voltage determiner searches for a detector voltage at which the median of the wave-height values in the wave-height-value list falls within a reference range.