RF Ion Guide Orthogonal Sampling for Mass Spectrometry
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Solution Overview
Problem
Mass spectrometers with discontinuous ion delivery suffer from low duty cycles due to the need for time gaps between ion pulses, especially at atmospheric and low pressures, which limits analytical performance and efficiency.
Innovation Solution
A mass spectrometer with an RF ion guide maintained at specific pressures and equipped with DC and RF potentials for orthogonal sampling, allowing continuous ion beam confinement and efficient orthogonal extraction, thereby increasing duty cycle without compromising analytical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If discontinuous ion delivery is used for mass spectrometry analysis, then separation and identification of individual components can be achieved, but duty cycle becomes low due to time gaps between ion pulses
Solution Approach 1:
The patent implements continuous ion delivery by maintaining a continuous ion beam through the ion guide while performing orthogonal sampling. This eliminates the need for time gaps between ion pulses, allowing the ion source to operate continuously and achieve duty cycles approaching 100%, while still enabling separation and identification through the orthogonal sampling mechanism
Solution Approach 2:
The patent introduces orthogonal sampling where ions are sampled perpendicular to the main ion beam direction. This dimensional change allows continuous ion delivery along the axial direction while enabling separation in the orthogonal direction, resolving the contradiction between continuous delivery and component separation
2Measurement precision
If narrow pulse gating is applied to continuous ion beam, then analytical performance improves, but duty cycle decreases due to loss of remaining ion beam
Solution Approach 1:
The ion guide maintains continuous ion confinement and transmission along the axial direction, ensuring that the ion beam remains continuous throughout the device. This eliminates the duty cycle loss associated with narrow pulse gating while preserving analytical performance through orthogonal sampling
Solution Approach 2:
The patent extracts a portion of ions from the continuous beam through orthogonal sampling, taking out the necessary ions for analysis while leaving the remainder of the continuous beam intact for subsequent sampling events, thereby maintaining high duty cycle
3Productivity
If RF ion traps are used for ion accumulation, then duty cycle approaches 100%, but efficient trapping is difficult at atmospheric and very low pressures
Solution Approach 1:
The patent uses orthogonal sampling perpendicular to the ion beam direction to achieve ion accumulation and analysis. This dimensional approach enables 100% duty cycle at atmospheric and very low pressures without requiring RF ion traps, as ions are continuously guided and sampled in the orthogonal direction
Solution Approach 2:
The patent replaces the RF ion trap mechanism with an orthogonal sampling system that uses electric fields applied perpendicular to the ion beam. This substitution eliminates the pressure-dependent trapping efficiency problem while maintaining high duty cycle performance
4Measurement precision
If orthogonal extraction is performed at very low pressures, then high resolution time of flight analysis is achieved, but pressure constraints limit applicability
Solution Approach 1:
The patent performs orthogonal sampling perpendicular to the ion beam direction, which enables high resolution analysis without requiring very low pressures. The orthogonal geometry minimizes collisions with background gas while maintaining the ability to achieve high resolution, thereby extending applicability to atmospheric and broader pressure ranges
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 solution achieves high duty cycles, up to 95%, by maintaining ions within the ion guide through radial pseudo-potentials and orthogonal sampling, enhancing the analytical efficiency and resolution of mass spectrometry.
Implementation Method 1
The ion guide comprises a drift tube wherein in a mode of operation a continuous, quasi-continuous or pulsed beam of ions is orthogonally sampled from the ion guide and wherein the continuous, quasi-continuous or pulsed beam of ions is not axially trapped or otherwise axially confined within the ion guide
Implementation Method 2
A mass spectrometer with an RF ion guide maintained at specific pressures and equipped with DC and RF potentials for orthogonal sampling, allowing continuous ion beam confinement and efficient orthogonal extraction
Data Source
Figure 1~2
Figure 3
Figure 4A~4B
AI summary
A mass spectrometer is disclosed comprising a RF ion guide wherein in a mode of operation a continuous, quasi-continuous or pulsed beam of ions is orthogonally sampled from the ion guide and wherein the continuous, quasi-continuous or pulsed beam of ions is not axially trapped or otherwise axially confined within the RF ion guide. The ion guide is maintained, in use, at a pressure selected from the group consisting of: (i) 0.0001 -0.001 mbar; (ii) 0.001 -0.01 mbar; (iii) 0.01 -0.1 mbar; (iv) 0.1 -1 mbar; (v) 1 -10 mbar; (vi) 10-100 mbar; and (vii) > 100 mbar.