RF Ion Trap Loading with Dynamic RF for Broad m/z Trapping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional linear ion traps exhibit poor trapping efficiency for large m/z ions at low applied RF voltage, leading to unstable motion of low m/z ions and a need for separate sample runs to process ions with a wide range of m/z ratios, which decreases the duty cycle and sensitivity in mass spectrometry.
Innovation Solution
A method involving a collision cell that traps ions with varying RF voltage applied to a mass analyzer, decreasing from a first value to a second value as ions are received, allowing efficient trapping and release of ions with a wide range of m/z ratios through mass selective axial ejection, and optionally using gas pressure pulses for cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the applied RF voltage is increased to improve trapping efficiency of large m/z ions, then the trapping efficiency of large m/z ions is improved, but the motion stability of low m/z ions deteriorates
Solution Approach 1:
The patent applies dynamics by making the RF voltage amplitude variable rather than fixed. The system dynamically adjusts the RF voltage amplitude based on the m/z ratio of ions being trapped, using different voltage levels for different ion mass ranges. This resolves the contradiction by allowing high voltage for large ions and low voltage for small ions at different times, rather than being constrained to a single fixed voltage level.
Solution Approach 2:
The patent changes the parameter of RF voltage amplitude to resolve the contradiction. By varying the RF voltage amplitude according to the ion m/z ratio, the system can optimize trapping conditions for each ion type. The method implements parameter changes by adjusting the RF voltage to match the specific trapping requirements of different ion masses, thereby achieving both high trapping efficiency and motion stability across the full m/z range.
2Productivity
If separate sample runs are used to process ions with different m/z ratios, then the trapping efficiency for each ion type is improved, but the duty cycle and sensitivity deteriorate
Solution Approach 1:
The patent implements continuity of useful action by enabling continuous trapping and analysis of ions across the entire m/z range in a single sample run. Instead of interrupting the analysis to perform separate runs for different ion types, the system continuously adjusts the RF voltage amplitude to accommodate varying ion masses, maintaining uninterrupted analysis and maximizing the duty cycle.
Solution Approach 2:
The dynamic adjustment of RF voltage amplitude allows the system to adapt to different ion types in real-time during a single continuous run. This eliminates the need for separate sample runs while maintaining optimal trapping conditions for each ion type, thereby resolving the contradiction between trapping efficiency and duty cycle.
3Productivity
If separate sample runs are used to process ions with different m/z ratios, then the trapping efficiency for each ion type is improved, but the sensitivity deteriorates
Solution Approach 1:
By maintaining continuous operation without interrupting for separate runs, the system accumulates more ions for detection over time. This continuous accumulation improves signal strength and detection sensitivity while maintaining high trapping efficiency through dynamic RF voltage adjustment, thereby resolving the contradiction between trapping efficiency and 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 enhances the trapping efficiency of both high and low m/z ions, improving the duty cycle and sensitivity by allowing efficient processing of ions across a broad m/z range, potentially doubling the mass analysis duty cycle.
Implementation Method 1
a mass analyzer having a plurality of rods to at least one of which an RF (radiofrequency) voltage is applied
Implementation Method 2
One or more RF voltages can be applied to one or more rods of the collision cell to generate an electromagnetic field for radially confining ions within the collision cell
Implementation Method 3
one or more electrodes disposed in the proximity of the entrance and/or exit of the collision cell can be employed to apply an axial electric field to the collision cell for providing axial confinement of ions
Data Source
AI summary
In one aspect, a method of processing ions in a mass spectrometer is disclosed, which comprises trapping a plurality of ions having different mass-to-charge (m/z) ratios in a collision cell, releasing said ions from the collision cell in a descending order in m/z ratio, and receiving the ions in a mass analyzer having a plurality of rods to at least one of which an RF voltage is applied, where the RF voltage is varied from a first value to a lower second value as the released ions are received by the mass analyzer.