Quadrupole Rod Set Contamination Control via Periodic Mode Switching
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Solution Overview
Problem
Quadrupole rod set mass filters face contamination issues due to ion beam-related contamination, leading to non-conductive layers forming on the rods, which alter the fields and affect analytical performance, especially with increasingly bright ion sources.
Innovation Solution
Implementing a control system that operates the quadrupole rod set in a resolving mode when ions of interest are present and a non-resolving or transmission mode when no ions of interest are present, minimizing ion impact on the rods and preventing layer formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the quadrupole rod set operates in resolving mode to filter ions by mass to charge ratio, then ion separation performance is improved, but ion beam related contamination increases causing non-conductive layers to form on the rods
Solution Approach 1:
The quadrupole rod set alternates between resolving mode and transmission mode in a periodic cycle. During resolving mode, ions are filtered by mass to charge ratio with the quadrupole operating with both RF and DC voltages. During transmission mode, the quadrupole operates in RF-only mode to transmit all ions without mass selection. This periodic switching prevents continuous ion impact on the rods, reducing contamination buildup while maintaining ion separation performance when needed.
Solution Approach 2:
The operating mode of the quadrupole rod set is made dynamic rather than static. The control system adjusts the quadrupole's voltage configuration in real-time, transitioning between resolving mode (with both RF and DC voltages applied for mass filtering) and transmission mode (with RF-only operation for full transmission). This dynamic adaptation allows the system to optimize between ion separation and contamination prevention based on operational requirements.
2Measurement precision
If the quadrupole rod set operates in resolving mode to select ions by mass to charge ratio, then analytical accuracy is improved, but ion impact on rods increases reducing instrument robustness
Solution Approach 1:
The system implements periodic switching between resolving mode for accurate mass analysis and transmission mode for robust operation. The control system cycles the quadrupole through resolving mode when analytical accuracy is required, then switches to transmission mode to allow all ions to pass through without impacting the rods, thereby preventing contamination and maintaining instrument robustness over time.
Solution Approach 2:
The transmission mode operation ensures continuous useful action by allowing all ions to be transmitted through the quadrupole without mass selection. This continuous transmission prevents ion accumulation and contamination on the rods, maintaining the instrument's robustness and reliability while complementing the resolving mode operations for comprehensive analytical capability.
3Adaptability or versatility
If the quadrupole rod set operates in resolving mode with both RF and DC voltages, then mass filtering capability is improved, but non-conductive layer formation increases altering the fields
Solution Approach 1:
The quadrupole rod set periodically alternates between resolving mode (with both RF and DC voltages for mass filtering) and transmission mode (with RF-only operation). This periodic switching prevents continuous ion impact that would form non-conductive layers, thereby maintaining field stability while preserving the mass filtering capability when resolving mode is activated.
Solution Approach 2:
The transmission mode operation, which allows all ions to pass through without mass selection, converts a potentially harmful continuous ion impact scenario into a beneficial cleaning mechanism. By periodically allowing unfiltered ion transmission, the system prevents the buildup of non-conductive layers that would otherwise alter the electric fields, thus maintaining field stability while preserving mass filtering capability.
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 minimizes ion buildup on the quadrupole rods, enhancing the accuracy and extending the lifetime and robustness of the quadrupole rod set by reducing contamination and maintaining optimal analytical performance.
Implementation Method 1
An RF voltage and a resolving DC voltage are simultaneously applied to the rod electrodes of the analytical quadrupole 1 so that the quadrupole rod set operates in a mass or mass to charge ratio resolving mode of operation
Implementation Method 2
ions having mass to charge ratios within a desired mass to charge ratio range will be onwardly transmitted by the mass filter, but undesired ions having mass to charge ratio values outside of the mass to charge ratio range will be substantially attenuated
Implementation Method 3
a separation device for separating ions temporally according to a first physico-chemical property
Data Source
AI summary
An apparatus for filtering ions is disclosed comprising a separation device for separating ions temporally according to a first physico-chemical property and a first quadrupole rod set for filtering ions according to their mass to charge ratio, wherein the first quadrupole rod set comprises a plurality of rods and wherein the first quadrupole rod set is arranged downstream of the separation device. The apparatus further comprises a control system arranged and adapted during a single cycle of separation of the separation device: (i) to operate the first quadrupole rod set in a first resolving mode of operation wherein ions of interest are selected by the first quadrupole rod set; and (ii) to operate the first quadrupole rod set in a second non-resolving or transmission mode of operation at separation times when substantially no ions of interest are present so that substantially no ions impact upon the rods of the first quadrupole rod set.