Ion Guide Voltage Control for Wide m/z Mass Spectrometry
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Solution Overview
Problem
The m/z range of ions that can stably pass a multipole ion guide is limited when high frequency voltage is shared with a quadrupole mass filter, leading to low sensitivity in mass spectrometry due to ions with large m/z differences being ejected.
Innovation Solution
A mass spectrometer system with an ion guide configured to apply an AC voltage offset by a DC voltage, where the acceleration voltage is controlled to increase with the mass-to-charge ratio of ions to be measured within a defined control region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If high frequency voltage is shared with the quadrupole mass filter, then the multipole ion guide can be inexpensive and effective for ion convergence, but the m/z range of ions that can stably pass is limited
Solution Approach 1:
The patent applies dynamic control of the DC voltage offset to the AC voltage applied to the ion guide. By dynamically adjusting the DC voltage component based on the m/z of ions to be measured, the system can adapt the ion guide's transmission characteristics to match different ion types, thereby expanding the usable m/z range while maintaining the cost-effective shared high frequency voltage configuration
Solution Approach 2:
The patent changes the voltage parameters (AC and DC components) applied to the ion guide based on the m/z of target ions. By adjusting these parameters, the system optimizes ion guide transmission for different mass ranges, resolving the contradiction between fixed configuration limitations and the need for broad adaptability
2Reliability
If the high frequency voltage is set for efficient passage of sample ions, then sample ions can be measured effectively, but ions with large m/z differences are ejected and sensitivity decreases
Solution Approach 1:
The system dynamically adjusts the voltage parameters applied to the ion guide based on real-time measurement requirements. When switching between different m/z ranges, the controller modifies the AC and DC voltage components to optimize transmission for the new ion type, preventing sensitivity loss during transitions while maintaining efficient measurement of sample ions
3Loss of time
If an electrode is inserted between ion guide rod electrodes to accelerate ions, then the time required for ions to pass is shortened and sensitivity is maintained, but the electrode becomes contaminated and charge up causes sensitivity to greatly decrease
Solution Approach 1:
The patent removes the physical electrode insertion approach and instead extracts only the necessary function (ion acceleration) by applying voltage control to the existing ion guide structure. This eliminates the contamination problem associated with inserted electrodes while maintaining the ion acceleration function needed to reduce passage time and preserve sensitivity
4Force
If an ion guide rod electrode is inclined or a tapered rod electrode is used to apply quadrupole electrostatic voltage, then axial electric field is formed, but the m/z range of ions that can pass is limited
Solution Approach 1:
The patent changes the voltage parameters (both AC and DC components) applied to the ion guide to expand the m/z range. By adjusting these electrical parameters, the system achieves broader ion transmission capability without modifying the physical geometry of the rod electrodes, thus maintaining the electric field function while increasing adaptability
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 allows for efficient mass spectrometry by ensuring ions across a wide m/z range can pass the ion guide without loss, thereby enhancing sensitivity and reducing time lag during m/z changes.
Implementation Method 1
a power source configured to apply an AC voltage at least to the ion guide, the AC voltage being offset by a DC voltage
Implementation Method 2
The voltage controller is configured to control an acceleration voltage by controlling the power source, the acceleration voltage being the DC voltage
Implementation Method 3
an ion guide disposed downstream of the ion source and configured to cause the ions to converge
Data Source
AI summary
A mass spectrometer includes an ion source, an ion guide, a quadrupole mass filter, a detector, DC and RF power sources, and a voltage control device for controlling an acceleration voltage by controlling the power source. The voltage controller controls the acceleration voltage such that it is increased as the mass-to-charge ratio of ions to be measured is increased within a control region. The control region is surrounded, having one coordinate axis representing the mass-to-charge ratio of the ions passing the ion guide and another axis representing the acceleration voltage applied to the ion guide, by a line representing a lower limit of a stable region where the ions pass the ion guide stably, a line representing an ion mobility of the ions, an upper side representing an upper limit of the acceleration voltage, and a lower side representing a value at which the acceleration voltage is zero.