High Pressure Ion Guide Axial Field Mass Filter
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Solution Overview
Problem
Conventional quadrupole rod set mass filters experience reduced performance at increased pressures due to axial cooling of ions, leading to prolonged transit times and increased exposure to electric fields, resulting in reduced ion transmission efficiency and contamination of analytical quadrupole rods, which requires costly maintenance and offline service.
Innovation Solution
A mass filter is arranged upstream of the analytical quadrupole, operating at high pressure with an axial force generated by DC voltages to drive ions through, reducing ion current and contamination by maintaining a lower mass resolution and coinciding transmission windows, thereby improving ion transmission efficiency and reducing rod contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional quadrupole rod set mass filters are operated at increased pressures, then the ion transmission efficiency is improved, but the ion transmission efficiency is reduced due to axial cooling of ions resulting in prolonged transit times and increased exposure to electric fields
Solution Approach 1:
The quadrupole rod set is divided into multiple axial segments, with each segment independently controllable. This segmentation allows the application of different voltages to different segments, enabling the creation of axial electric fields that accelerate ions through the device and reduce transit time, thereby resolving the contradiction between operating at high pressure and maintaining ion transmission efficiency.
Solution Approach 2:
The mass filter operates with dynamic voltage control where resolving DC and RF voltages are applied to create mass-selective filtering, while additional axial DC voltages are dynamically applied to segments to accelerate ions. This dynamic control allows the system to simultaneously achieve mass resolution and reduced transit time, resolving the contradiction between pressure operation and ion transmission efficiency.
2Quantity of substance
If conventional quadrupole rod set mass filters are operated at increased pressures, then the ion transmission efficiency is improved, but the rods become contaminated requiring costly maintenance and offline service
Solution Approach 1:
By segmenting the quadrupole rods into multiple axially-separated segments with independent voltage control, the invention creates a mass filter that can operate at high pressures with reduced ion transit times. This prevents ion accumulation and rod contamination, eliminating the need for costly maintenance and offline service while maintaining high ion transmission efficiency.
3Object-affected harmful factors
If a mass filter is placed upstream of the analytical quadrupole, then rod contamination is reduced, but the device complexity increases
Solution Approach 1:
The upstream mass filter is designed with multi-functionality, serving both as a contamination barrier for the analytical quadrupole and as a preliminary mass selection stage. By combining these functions in a single device with segmented control, the invention reduces overall system complexity compared to having separate dedicated components for each function.
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 significantly enhances ion transmission efficiency and reduces contamination of analytical quadrupole rods, allowing for operation at higher pressures without the need for high-performance vacuum pumps, thus lowering the cost and complexity of mass spectrometers.
Implementation Method 1
a first device arranged and adapted to generate an axial force which drives at least some ions axially through or along the first mass filter
Implementation Method 2
A RF voltage and a resolving DC voltage are simultaneously applied to the rod electrodes so that the mass filter operates in a mass or mass to charge ratio resolving mode of operation
Data Source
AI summary
A mass spectrometer is disclosed comprising a first mass filter comprising a plurality of electrodes and a first device arranged and adapted to generate an axial force which drives at least some ions axially through or along the first mass filter and a quadrupole mass filter or mass analyzer arranged downstream of the mass filter.