Segmented Ion Guide for High-Pressure Mass Spectrometry
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Solution Overview
Problem
Current mass spectrometers face challenges in efficiently guiding and separating ions based on their mass-to-charge ratio, particularly at high pressures, where ion-molecule collisions lead to fragmentation and inefficient ion transmission.
Innovation Solution
The design incorporates an ion guide or ion trap with a specific configuration of electrodes and voltages, where ions are radially and axially confined using RF and DC potentials, allowing for controlled release based on mass-to-charge ratio through varying extraction electric fields and aperture sizes, enabling mass separation without resonant ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ions are transferred through a high pressure region using RF ion guides, then ion transmission is enabled, but ion-molecule collisions cause fragmentation and reduce transmission efficiency
Solution Approach 1:
The ion guide is divided into multiple rod segments arranged in multipole configurations (quadrupole, hexapole, octapole). Each segment can be independently controlled with RF and DC voltages, allowing creation of localized potential wells that guide ions through the high pressure region without fragmentation while maintaining transmission efficiency.
Solution Approach 2:
The patent applies dynamic voltage control to the rod segments, using time-varying RF and DC potentials to create moving potential wells that actively guide ions through the pressure gradient. This dynamic control allows ions to be steered through the high pressure region without collisions that would cause fragmentation.
2Productivity
If conventional ion guides are used at high pressure, then ion transfer is possible, but ion-molecule collisions lead to loss of ion signal
Solution Approach 1:
The patent creates preliminary potential wells using RF and DC voltages on the rod segments before ions enter the high pressure region. These pre-formed potential structures guide ions along optimized trajectories that minimize exposure to collision-prone regions, enabling efficient ion transfer while reducing signal loss from ion-molecule collisions.
3Measurement precision
If mass separation is performed using conventional methods, then ions can be separated by mass-to-charge ratio, but the duty cycle and sensitivity of the mass analyzer are reduced
Solution Approach 1:
The patent uses variable DC offsets applied to different rod segments to dynamically adjust the potential landscape for mass separation. By changing the voltage parameters on the segmented rods, ions of different mass-to-charge ratios are separated through the potential wells while maintaining continuous ion flow, thus preserving both separation precision and analyzer 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 configuration improves ion transmission efficiency, prevents fragmentation, and allows for selective mass release, enhancing the duty cycle and sensitivity of mass analyzers by operating at high pressures without ion fragmentation.
Implementation Method 1
A first AC or RF voltage is applied to at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95% or 100% of the first electrodes
Implementation Method 2
A second DC voltage is applied to at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95% or 100% of the first electrodes
Implementation Method 3
an extraction electric field is applied along at least a portion of the length of the ion guide or ion trap during the first time period Te in order to accelerate at least some ions out of the ion guide or ion trap
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
An ion guide or ion trap (1) is disclosed having an entrance electrode (2) and an exit electrode (3). The potential of the exit electrode (3) is periodically dropped for a relatively short period of time allowing some ions to escape from the ion guide or ion trap (1) via an aperture in the exit electrode (3). The period of time that the potential of the exit electrode (3) is dropped for is progressively increased and ions emerge from the ion guide or ion trap (1) in a mass to charge ratio dependent manner. The ion guide or ion trap (1) may be operated as a mass separator or low resolution mass analyser.