Ion Trap Voltage Control for Mass Spectrometer Waveform Stability
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Solution Overview
Problem
Existing mass spectrometers using MALDI ion sources face inefficiencies in ion capture due to waveform deformation of square-wave voltage in ion traps and insufficient ion generation per laser pulse, leading to suboptimal S/N ratios in mass spectrometry.
Innovation Solution
A mass spectrometer design that generates ions at multiple phase time points during the periodic voltage application, synchronizing laser light emission with ion trap phases to prevent waveform deformation and enhance ion capture efficiency, allowing for increased ion acquisition and wider mass range detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the square-wave voltage is increased from 0V to capture ions efficiently, then ion capture efficiency is improved, but waveform deformation occurs due to large current load change in the power supply
Solution Approach 1:
The patent applies preliminary action by pre-charging the ring electrode to a predetermined voltage level before ion introduction. This prevents the large current load change that occurs when switching from 0V, thereby avoiding waveform deformation while maintaining efficient ion capture. The electrode is prepared in advance at the optimal voltage level rather than switching during the process.
2Quantity of substance
If ions are introduced additionally into the ion trap to improve S/N ratio, then the number of detected ions is increased, but ion capture efficiency decreases due to electric field interference
Solution Approach 1:
The patent employs periodic action by cycling the ring electrode voltage between a first level (for efficient ion capture) and a second level (for additional ion introduction). This periodic voltage modulation allows the system to alternately optimize for capture efficiency and ion quantity, achieving both goals through time-separated operations rather than simultaneous conflicting conditions.
3Productivity
If laser light emission timing is synchronized with ion trap phases, then ion capture efficiency is improved, but the system complexity increases due to precise timing control requirements
Solution Approach 1:
The patent implements feedback control by monitoring the actual voltage phase and timing of laser emission, and adjusting the relative timing between laser pulses and voltage cycles. This feedback mechanism ensures precise synchronization without requiring overly complex predetermined timing systems, as the system self-corrects to maintain optimal alignment between ion generation and trap capture phases.
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 prevents waveform deformation of the periodic voltage, efficiently captures ions, and increases the number of ions detected per mass spectrometry event, improving the S/N ratio and enabling the capture of ions across a wider mass range without specific mass restrictions.
Implementation Method 1
In the MALDI ion source, a sample matrix mixture is irradiated with laser light, which is an ultraviolet ray. The laser light is emitted in the pulse form. Thus, the pulse-form ions are generated from the MALDI ion source.
Implementation Method 2
A cooling gas is supplied into the ion trap in advance, and the kinetic energy of the captured ions is reduced by the cooling gas. Thus, the ions are stably captured in the ion trap.
Implementation Method 3
Then, a high frequency voltage is added to the end-cap electrode of the ion trap, so that the ions having a specific mass are resonantly excited, and the excited ions are discharged from the ion trap.
Data Source
AI summary
A mass spectrometer includes an ion source that generates ions, an ion trap that captures the ions generated from the ion source, a detector that detects the ions ejected from the ion trap and a controller that controls a periodic voltage, which is added to form a capturing electric field in the ion trap and controls a time point at which the ions are generated from the ion source. The controller includes an ion generation time controller that allows the ions to be generated from the ion source at N (N is an integer equal to or larger than 2) phase time points while addition of the periodic voltage is continued, the N phase time points being set in one period of the periodic voltage and being respectively assigned to different periods of the periodic voltage.