High-Pressure Ion Guide RF Control for Charge State Switching
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Solution Overview
Problem
Conventional mass spectrometry systems face challenges in maintaining the isotopic distribution of ions due to unintentional electron detachment in high-pressure ion guides, leading to aberrations in ion analysis and distortion of charge state distributions.
Innovation Solution
The system controls electron detachment by adjusting the RF voltage signal amplitude in the high-pressure ion guide to maintain or enhance electron detachment, allowing for accurate isotopic distribution and controlled fragmentation of ions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ions are transmitted through a high-pressure ion guide, then collisional cooling and radial focusing are achieved, but unintentional electron detachment occurs causing charge state distortion
Solution Approach 1:
The system dynamically adjusts the RF voltage amplitude based on the desired operational mode. By making the RF voltage a variable parameter rather than a fixed value, the system can adapt to maintain ions in high charge states for MS analysis or allow electron detachment for MS/MS fragmentation, resolving the contradiction between stable transmission and charge state control
Solution Approach 2:
The patent changes the RF voltage amplitude parameter to control the degree of electron detachment. By adjusting this physical parameter, the system transitions between maintaining intact charge states (lower RF amplitude) and inducing controlled electron detachment (higher RF amplitude), thereby controlling the charge state distribution while maintaining reliable ion transmission
2Manufacturing precision
If RF voltage amplitude is increased to maintain charge states, then isotopic distribution is preserved, but controlled fragmentation capability is reduced
Solution Approach 1:
The system uses dynamic adjustment of RF voltage amplitude to switch between two operational modes: a first mode with lower amplitude that preserves isotopic distribution for accurate mass determination, and a second mode with higher amplitude that enables controlled electron detachment and fragmentation for structural analysis. This dynamic parameter control provides versatility while maintaining precision in each mode
3Stability of the object's composition
If conventional transmission without modification is used, then ion integrity is maintained, but control over charge state and fragmentation is lost
Solution Approach 1:
The system implements feedback control by monitoring the operational requirements and adjusting the RF voltage amplitude accordingly. The controller receives information about the desired analysis mode (MS or MS/MS) and automatically adjusts the RF voltage to maintain ion integrity when needed or to induce controlled electron detachment when fragmentation is required, providing ease of operation while maintaining control
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 more accurate mass determination and structural analysis of ions by maintaining or altering their charge states, improving data deconvolution and characterization in mass spectrometry.
Implementation Method 1
the plurality of rods being spaced apart from the central longitudinal axis and configured to define an internal volume within which the plurality of ions received through the inlet aperture are entrained by a flow of gas. A power supply coupled to the ion guide can be configured to provide a RF voltage signal to the plurality of rods for radially confining the ions within the internal volume
Implementation Method 2
the plurality of rods being spaced apart from the central longitudinal axis and configured to define an internal volume within which the plurality of ions received through the inlet aperture are entrained by a flow of gas
Implementation Method 3
ions pass through an inlet orifice to enter an ion guide disposed in a first vacuum chamber where they are collisionally cooled and radially focused along the central axis of the ion guide
Data Source
AI summary
Systems and methods described herein provide for charge state control of multiply-charged anions in a front end, high pressure ion guide. In some example aspects, a mass spectrometer system is provided comprising a first vacuum chamber (121) maintained at a pressure above about 500 mTorr. At least one ion guide (106) is disposed within the first vacuum chamber, the at least one ion guide comprising a plurality of rods extending along a central longitudinal axis. A controller (193) is configured to adjust an amplitude of an RF voltage signal provided to the plurality of rods so as to alternatively operate the ion guide in a first mode of operation with a lower amplitude of the RF voltage signal so as to reduce the likelihood of charge reduction by electron detachment so as to substantially maintain the isotopic distribution of the ions during transmission of ions through the ion guide, and a second mode of operation with a higher amplitude of the RF voltage signal so as to increase the likelihood of electron detachment from ions being transmitted therethrough.