Emitter Current Control for Mass Spectrometry Peak Tailing
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Solution Overview
Problem
Existing mass spectrometry systems face challenges in balancing the prevention of specimen adhesion on the emitter surface with maintaining measurement sensitivity, as constant emitter current settings fail to account for varying specimen conditions and measurement situations.
Innovation Solution
A dynamic control system that adjusts emitter current parameters based on peak shape evaluation, optimizing current values and durations to minimize specimen adhesion while enhancing sensitivity by using a controller to generate and apply multiple provisional parameters, and determining optimal settings through an evaluation value table.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a constant emitter current is applied to the emitter, then the specimen adhesion can be prevented to some extent, but the measurement sensitivity is reduced due to continuous heating
Solution Approach 1:
The patent applies periodic action by intermittently supplying emitter current to the emitter rather than continuously. The current is supplied in cycles during the measurement period, allowing the emitter temperature to be controlled dynamically. This periodic supply prevents excessive heating that reduces sensitivity while still providing enough heating to prevent specimen adhesion during critical phases.
Solution Approach 2:
The patent implements dynamics by making the emitter current supply adaptable to measurement conditions. The current supply is controlled based on the measurement period and can be adjusted dynamically rather than remaining constant. This allows optimization of both adhesion prevention and sensitivity maintenance by adapting the heating pattern to actual measurement needs.
2Object-affected harmful factors
If a large amount of emitter current is applied, then specimen residue is prevented, but measurement sensitivity is reduced
Solution Approach 1:
The patent applies partial action by supplying emitter current only during specific periods of the measurement cycle rather than continuously at full strength. The current is applied partially in terms of time duration, which is sufficient to prevent specimen residue accumulation while avoiding excessive heating that would reduce measurement sensitivity during actual detection phases.
3Measurement precision
If the emitter current is reduced to maintain sensitivity, then measurement sensitivity is improved, but specimen adhesion and residue occur more easily
Solution Approach 1:
The patent uses periodic action to alternate between current supply phases (preventing adhesion) and measurement phases (maintaining sensitivity). During measurement phases, current is reduced or stopped to maintain sensitivity, while during intervals, current is supplied to prevent adhesion, creating a rhythmic pattern that balances both requirements.
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
The system effectively reduces specimen adhesion on the emitter while maintaining or improving measurement sensitivity by dynamically controlling emitter current, ensuring superior peak shapes and overall sensitivity throughout the measurement process.
Implementation Method 1
a high voltage is applied between an emitter functioning as an anode and an electrode functioning as a cathode. With the high voltage, a strong electric field is generated near the emitter. The specimen is ionized by the electric field.
Implementation Method 2
a current is applied to the emitter to heat the emitter, and to vaporize the specimen adhered to the emitter
Implementation Method 3
a gas chromatograph apparatus arranged to timewise separate a plurality of compounds in a mixture specimen based on a difference in mobility of the compounds
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
Mass spectrometry for a specimen is repeatedly performed while stepwise changing a parameter (for example, a current value) of an emitter current. Based on a plurality of chromatograms (62-70) generated by this process, an evaluation value table (74, 92) including a plurality of evaluation values is generated. An individual evaluation value shows a degree of tailing for individual peak included in each chromatogram. A parameter function (102, 104, 106) is generated based on the evaluation value table (74, 92). The parameter of the emitter current is controlled according to the parameter function (102, 104, 106).