Skimmer Adsorbent Traps Deposition to Reduce Memory Effects
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Solution Overview
Problem
The throughput of inductively coupled plasma mass spectrometry (ICP-MS) instruments is reduced due to material deposition on the skimmer cone and sampling cone surfaces, leading to memory effects that affect analysis accuracy and require frequent maintenance.
Innovation Solution
A skimmer apparatus with a plasma-separation mechanism that separates deposited material from the skimmed plasma within the skimmer cone, preventing it from reaching the ion extraction optics, and an adsorbent material on the internal surface to trap and remove deposited matter, reducing contamination and memory effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional skimmer cone is used to skim plasma, then ion beam formation is achieved, but material deposition on the skimmer cone surface occurs leading to memory effects and reduced throughput
Solution Approach 1:
The patent extracts and removes the deposited material from the skimmer cone surface using a plasma cleaning system. The cleaning plasma is generated within the skimmer cone and selectively removes deposited ions and molecules from the surface, preventing memory effects while maintaining continuous operation and high throughput
Solution Approach 2:
The patent implements continuous plasma cleaning during instrument operation to maintain the skimmer cone surface. By continuously removing deposited material, the system prevents memory effects without interrupting analysis, thereby maintaining both high accuracy and high throughput throughout extended operation periods
2Reliability
If the skimmer cone surface is cleaned frequently to remove deposited material, then memory effects are reduced, but instrument downtime and maintenance requirements increase
Solution Approach 1:
The plasma cleaning system operates continuously during normal instrument operation, constantly removing deposited material from the skimmer cone surface. This eliminates the need for periodic maintenance interruptions while maintaining stable, memory-free analysis throughout extended operation periods
Solution Approach 2:
The system uses plasma generated during normal operation to automatically clean the skimmer cone surface. The cleaning process is self-sustaining and requires no external intervention or maintenance, as the plasma environment inherent to ICP-MS operation is utilized to remove deposits in real-time
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
Significantly reduces memory effects by minimizing the impact of deposited ions on subsequent plasma analysis, maintaining instrument stability and throughput, and reducing the need for frequent maintenance.
Implementation Method 1
The sampled plasma expands downstream of the sampling cone, into an evacuated expansion chamber
Implementation Method 2
This typically involves a number of stages of pressure reduction, extraction of the ions from the plasma and ion beam formation
Implementation Method 3
an adsorbent material on the internal surface to trap and remove deposited matter, reducing contamination and memory effects
Implementation Method 4
The central portion of the expanding plasma then passes through a second aperture, provided by a skimmer cone, into a second evacuation chamber having a higher degree of vacuum. As the plasma expands through the skimmer cone, its density reduces sufficiently to allow extraction of the ions to form an ion beam, using strong electric fields generated by ion lenses downstream of the skimmer cone
Implementation Method 5
A radio frequency electric current is supplied to the torch coil and the resulting alternating magnetic field causes the free electrons to be accelerated to bring about further ionization of the plasma gas
Implementation Method 6
The carrier gas and nebulized sample flow through the central torch channel and pass into the central region of the plasma, where the temperature is high enough to cause atomization and then ionization of the sample
Data Source
AI summary
A method of preparing or operating a mass spectrometer vacuum interface comprising a skimmer apparatus having a skimmer aperture and an internal surface of the skimmer apparatus, comprising disposing an adsorbent or getter material on the internal surface. The internal surface has a deposition region where matter from plasma flows may be deposited and the material is disposed on part or all of the deposition region. The disposing step may be performed before a first use and/or intermittently, especially to refresh a previously disposed material. Providing such material serves to trap or collect deposition matter which might anyway be deposited but in such a way that subsequent liberation of that matter is prevented or at least reduced.