Switchable Ion Guide for Noding-Free Collision Cell Focusing
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Solution Overview
Problem
Multi-collector ICP-MS systems face challenges in achieving precise isotope ratio measurements due to elemental and molecular interferences, which can be exacerbated by the noding effect caused by RF-driven ion optics in collision cells, leading to ion beam scattering and focusing issues.
Innovation Solution
An ion optical arrangement for the collision cell that allows switching between pressurized and evacuated modes, using a radio frequency electric focusing field in the pressurized mode and a static electric focusing field in the evacuated mode, eliminating the need for RF-driven optics and reducing noding effects by segmenting multipole arrangements into einzel lens sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RF-driven ion optics are used in the collision cell to maintain ion beam focus in pressurized mode, then ion focusing is improved, but noding effects occur causing ion beam scattering and measurement precision degradation
Solution Approach 1:
The patent applies dynamics by making the ion optics configuration switchable between two states: RF-driven multipole configuration for pressurized mode and static Einzel lens configuration for evacuated mode. This dynamic adaptation allows the system to optimize ion focusing for each operational mode while avoiding the harmful noding effect that occurs with RF-driven optics in evacuated mode
Solution Approach 2:
The patent changes the operational parameters of the ion optics by switching between RF voltage application and static voltage application. In pressurized mode, RF voltages are applied to create multipole fields for ion focusing. In evacuated mode, the system transitions to static voltages creating Einzel lens fields, thereby eliminating the noding effect while maintaining focusing capability
2Measurement precision
If the collision cell operates in pressurized mode to remove chemical interferences, then interference removal is improved, but ion beam scattering increases reducing transmission efficiency
Solution Approach 1:
The system dynamically switches between pressurized and evacuated modes of the collision cell depending on the analytical requirements. When chemical interference removal is needed, the cell is pressurized with collision gas. When high transmission efficiency is the priority and interferences are minimal, the cell is evacuated to minimize ion beam scattering
Solution Approach 2:
The patent changes the pressure parameter of the collision cell operating mode. By controlling the gas pressure in the collision cell and switching between pressurized and evacuated states, the system optimizes the balance between interference removal capability and ion beam transmission efficiency for different analytical scenarios
3Measurement precision
If a dual path ion optics arrangement is implemented to bypass the collision cell, then noding effects are eliminated, but device complexity increases with multiple deflectors and alignment problems
Solution Approach 1:
The patent makes the single collision cell serve multiple functions by enabling it to operate in both pressurized and evacuated modes. The same physical collision cell structure can function as an RF-driven multipole for interference removal when pressurized, or as a static Einzel lens for high-precision transmission when evacuated, eliminating the need for separate bypass paths
Solution Approach 2:
The patent merges the functions of what would traditionally require separate beam paths into a single unified ion optical system. The collision cell is designed to accommodate both RF-driven and static field configurations, combining the interference removal capability with the high-precision transmission capability in one integrated structure rather than requiring dual path arrangements
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 solution enables precise isotope ratio measurements by maintaining ion beam focus in both operation modes, reducing ion scattering, and eliminating noding effects, thus enhancing the accuracy and reliability of isotope ratio analysis without the complexity of dual path ion optics.
Implementation Method 1
using a radio frequency electric focusing field in the pressurized mode
Implementation Method 2
using a static electric focusing field in the evacuated mode
Implementation Method 3
the chemical interferences are removed by chemical reactions
Implementation Method 4
by kinetic energy discrimination, taking advantage of different cross sections of molecular and elemental species inside the pressurized collision cell which results in different kinetic energy losses of molecular and elemental ions
Data Source
AI summary
An ion optical arrangement (1) for use in a mass spectrometer comprises a collision cell defining an ion optical axis along which ions may pass, electrodes comprising a set of parallel poles (11A, 11B, 11C) arranged in the collision cell, and a voltage source for providing voltages to the electrodes to produce electric fields. The ion optical arrangement is arranged for switching between a first operation mode in which the collision cell is pressurized and a second operation mode in which the collision cell is substantially evacuated. The ion optical arrangement is further arranged for producing a radio frequency electric focusing field in the first operation mode and a static electric focusing field in the second operation mode.