Mass Spectrometer Bidirectional Ion Mobility Separation
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Solution Overview
Problem
Mass spectrometers face challenges in effectively separating and identifying ions in highly complex mixtures due to limited peak capacity and ion mobility separation capabilities, especially when sample complexity increases, leading to difficulties in selecting individual precursor ions for fragmentation.
Innovation Solution
A mass spectrometer design incorporating a multipole rod set or segmented multipole rod set ion trap with a quadrupole, hexapole, or octapole configuration, combined with an ion mobility spectrometer, allows for improved ion mobility separation by using a combination of DC and RF voltages to confine and separate ions, enabling the transmission of ions in both directions through the ion trap and mobility spectrometer for enhanced separation and fragmentation capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single ion mobility separation stage is used, then the device complexity is reduced, but the peak capacity and separation capability are limited
Solution Approach 1:
The patent combines ion mobility separation with the ability to pass ions in both directions through the same separation stage. By merging the functions of separation and bidirectional ion transmission in a single stage, the system achieves enhanced peak capacity without adding multiple separate separation devices, thus reducing overall device complexity while maintaining high separation capability.
Solution Approach 2:
The system dynamically switches the direction of ion flow through the ion mobility separation stage. By making the ion transmission direction variable (upstream or downstream), the single separation stage can perform multiple separation functions that would traditionally require multiple fixed stages, thereby increasing peak capacity without proportionally increasing device complexity.
2Productivity
If ions are passed back upstream through the ion mobility spectrometer, then ion transmission efficiency is improved, but the device complexity increases
Solution Approach 1:
The ion mobility separation stage is designed to serve multiple functions: it can separate ions while allowing bidirectional ion flow (upstream and downstream). This multi-functionality enables the system to improve ion transmission efficiency by passing ions back upstream without requiring additional specialized components, thus avoiding a proportional increase in device complexity.
Solution Approach 2:
The ion mobility separation stage itself provides the capability for bidirectional ion transmission without requiring external auxiliary systems. The stage uses its own electric field configuration to guide ions in either direction, making the system self-sufficient and avoiding the need for additional complex control mechanisms that would increase device complexity.
3Manufacturing precision
If multiple ion mobility separation stages are used, then the peak capacity increases, but the device complexity and instrument length increase
Solution Approach 1:
The patent merges multiple separation functions into a single ion mobility separation stage by enabling bidirectional ion flow. This allows the system to achieve the peak capacity equivalent of multiple stages without physically adding multiple separation devices, thereby increasing peak capacity while keeping the instrument length compact.
Solution Approach 2:
The system adds the dimension of time and direction control to the ion flow through the separation stage. By allowing ions to pass back upstream and undergo additional separation cycles in the same physical space, the system effectively creates a temporal dimension for separation that multiplies the peak capacity without increasing the spatial footprint or instrument length.
4Manufacturing precision
If multiple ion mobility separation stages are used, then the peak capacity increases, but the device complexity increases
Solution Approach 1:
The patent combines multiple separation functions into a single ion mobility separation stage by enabling bidirectional ion flow. This merging of functions allows the system to achieve high peak capacity equivalent to multiple stages without proportionally increasing the number of components, thus resolving the contradiction between peak capacity and device complexity.
Solution Approach 2:
The system uses dynamic control of ion flow direction to multiply the separation capability of a single separation stage. By making the ion transmission path variable (allowing ions to pass back upstream), the system achieves the functional equivalent of multiple static stages without adding the corresponding number of physical components, thereby increasing peak capacity while keeping device complexity manageable.
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 design enhances the peak capacity and flexibility of the mass spectrometer, enabling the separation and identification of complex ion mixtures by allowing ions to be passed back upstream through a single ion mobility separation stage, improving ion transmission and fragmentation efficiency, and reducing the need for multiple stages, thus simplifying the instrument and increasing its analytical capabilities.
Implementation Method 1
One known method which may be used to separate ions prior to analysis by mass spectrometry is that of ion mobility spectrometry or gas phase electrophoresis. One form of an ion mobility spectrometer or separator comprises a drift tube or cell wherein an axial electric field is maintained in the presence of a buffer gas. Higher mobility ions pass more quickly along the length of the ion mobility spectrometer or separator than lower mobility ions.
Implementation Method 2
A known ion mobility spectrometer or separator operating under a partial vacuum comprises a plurality of electrodes having apertures. A DC voltage gradient is maintained along the length of the ion mobility spectrometer or separator and the electrodes are connected to an AC or RF voltage supply. This form of ion mobility spectrometer or separator is advantageous in that the AC or RF voltage which is applied to the electrodes results in radial confinement of the ions passing through the ion mobility spectrometer or separator.
Implementation Method 3
An ion mobility spectrometer or separator is known wherein ions are confined radially by an inhomogeneous RF field in an ion guide and ions are propelled forward by a potential hill or barrier that is progressively applied along the axis of the ion guide in the presence of a buffer gas. Appropriate selection of the amplitude and velocity of the potential hill or barrier which is translated along the length of the ion guide and the type and pressure of gas allows ions to slip selectively over the potential hill or barrier according to their ion mobility.
Data Source
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Figure 3A~3D
AI summary
A mass spectrometer is disclosed comprising a first ion trap or ion guide (2) , a single ion mobility spectrometer or separator stage (3) and a second ion trap or ion guide (4) arranged downstream of the ion mobility spectrometer or separator (3). In a mode of operation ions from the second ion trap or ion guide (4) are passed from the second ion trap or ion guide back upstream to the ion mobility spectrometer or separator (3).