Linear Trap Mass Spectrometer Resonant Ion Ejection
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Solution Overview
Problem
Current mass spectrometers face challenges in achieving high-speed charge separation, which leads to decreased sensitivity due to the trade-off between charge selectivity and sensitivity, requiring lengthy separation times and resulting in low usability of ions.
Innovation Solution
A mass spectrometer with a linear trap and an ion trap controller that applies a voltage with a frequency based on the mass-to-charge ratio to selectively eject ions with higher charges while retaining those with lower charges, using a supplemental AC voltage to resonate and eject ions with specific mass-to-charge ratios, thereby improving the duty cycle and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If charge separation is performed by lowering the potential barrier on the axis in a linear trap, then charge selectivity is improved, but separation time increases significantly, leading to decreased sensitivity
Solution Approach 1:
The patent applies a supplemental AC voltage to the end lenses that resonates with the harmonic potential formed by the RF voltage. This causes ions with specific mass-to-charge ratios to oscillate and be radially ejected from the trap, enabling rapid charge separation without requiring prolonged lowering of the potential barrier. The resonant vibration frequency is tuned to match the ion oscillation frequency, achieving selective ejection in a short time frame.
Solution Approach 2:
The patent employs periodic application of the supplemental AC voltage at specific frequencies to achieve charge separation. By applying the voltage periodically at the resonant frequency of the harmonic potential, ions are selectively ejected in a time-efficient manner. This periodic action allows the system to maintain high charge selectivity while significantly reducing the separation time compared to continuous potential barrier lowering.
2Productivity
If a supplemental AC voltage is applied to achieve rapid charge separation, then sensitivity is improved, but the complexity of voltage control increases
Solution Approach 1:
The end lenses in the linear trap serve multiple functions: they provide the harmonic potential for ion confinement through RF voltage, and simultaneously serve as the application point for the supplemental AC voltage for charge separation. This multi-functionality reduces the need for additional separate components and simplifies the overall voltage control architecture while achieving rapid charge separation and high sensitivity.
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 enables high-speed charge separation with a duty cycle of 50%, significantly improving the sensitivity of ion analysis by allowing for the selective passage of multiple charge ions and effective separation of ion mobility, six times more sensitive than previous methods.
Implementation Method 1
A supplemental AC voltage which resonates with the harmonic potential is applied to between electrodes opposed to each other to radially eject the ions with the specific mass-to-charge ratio
Implementation Method 2
a harmonic potential is formed radially by a RF voltage
Implementation Method 3
collision of gas molecules inside a linear trap allows ions to be cooled to the thermal temperature
Implementation Method 4
Ions ejected pulsely from an ion source or an ion trap are subjected to a constant DC electric field under gas pressure of approximately 10 mTorr. Since the velocities of ions accelerated by the electric field are different from each other, separation of the ion mobility is performed in an acceleration area of the DC electric field
Data Source
AI summary
A linear trap which allows for charge separation and ion mobility separation in a speedy manner, and enables measurement with high duty cycle. A mass spectrometer comprises an ion source, an ion trap for trapping ions ionized by the ion source, an ion trap controller for controlling a voltage on an electrode included in the ion trap, and a detector for detecting the ions ejected from the ion trap. The ion trap controller includes a table for each mass-to-charge ratio, the table containing a frequency of the voltage used for charge separation, and a gain of the voltage for ejecting a first ion with a first charge outside the ion trap, and retaining in the ion trap a second group of ions with a second charge that is lower than that of the first charge. The ion trap controller controls the voltage based on the mass-to-charge ratio set. The mass spectrometer has significantly improved sensitivity, as compared to the prior art.