Mass Spectrometer Ion Transit Time Control
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Solution Overview
Problem
Triple quadrupole mass spectrometers face complexity in timing control for ion selection by mass analyzers due to varying flight velocities of ions with different mass-to-charge ratios, leading to decreased analysis velocity and increased operational complexity.
Innovation Solution
Modifying the axial voltages on the first and second mass analyzers based on the mass-to-charge ratio of ions to maintain constant kinetic energies, allowing for easier timing control and reduced ion loss, while storing and ejecting ions as pulsed ions at regular intervals to enhance detection sensitivity and fragmentation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pulsed ions are produced by storing and ejecting ions to improve sensitivity, then detection sensitivity is improved, but timing control complexity increases
Solution Approach 1:
The patent applies parameter changes by varying the axial voltage on mass analyzers according to the mass-to-charge ratio of ions. This allows the kinetic energy of ions in the optical axis direction to be adjusted, thereby controlling flight velocity and transit time. By changing the voltage parameter dynamically, the system achieves simplified timing control while maintaining the pulsed ion operation for high sensitivity detection.
2Reliability
If constant kinetic energy is maintained for all ions regardless of mass-to-charge ratio, then flight velocity varies with mass, but this leads to varying transit times and complicates timing control
Solution Approach 1:
The patent changes the axial voltage parameter on mass analyzers based on the mass-to-charge ratio of selected ions. This ensures that ions with different masses have different kinetic energies in the optical axis direction, resulting in substantially constant transit times through the mass analyzer. This parameter adjustment simplifies timing control while maintaining accurate ion selection.
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 consistent ion transit times through the mass analyzers, simplifying timing control and improving detection sensitivity and fragmentation efficiency by maintaining constant axial voltages during ion passage, thereby reducing ion loss and interference.
Implementation Method 1
A quadrupole mass spectrometer is a mass spectrometer for passing only ions of desired mass-to-charge ratios by applying an RF voltage and a DC voltage to hyperbolic quadrupole rods
Implementation Method 2
The ions (precursor ions) selected by the first mass analyzer are guided to a collision cell, where the ions collide with gaseous molecules. Consequently, the ions are fragmented with some probability
Data Source
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AI summary
A mass spectrometer is offered which can easily control the timing at which ions selected by each mass analyzer (30, 50) are varied. The spectrometer has an ion storage portion (20) for storing ions created by an ion source (10) and ejecting the stored ions as pulsed ions, a first mass analyzer (30) for selecting first desired ions from the pulsed ions ejected from the storage portion (20) based on mass-to-charge ratio, a collision cell (40) for fragmenting some or all of the first desired ions into product ions, and a second mass analyzer (50) for selecting second desired ions from the first desired ions and the product ions based on mass-to-charge ratio, a detector (60) for detecting the second desired ions, and a controller (90) that provides control such that those of the first desired ions which have larger masses have larger kinetic energies in the direction of the optical axis (62) in the first mass analyzer (30) and that those of the second desired ions which have larger masses have larger kinetic energies in the direction of the optical axis (62) in the second mass analyzer (50) .