Membrane Purge Gas Transfer for Stable Laser Ablation ICP Sampling
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Solution Overview
Problem
Existing laser ablation systems face issues with atmospheric gas entering the inductively coupled plasma (ICP) torch during sample changeover, leading to plasma extinguishment and increased operational costs due to frequent mechanical failures and maintenance needs of pinch valves.
Innovation Solution
A gas exchange membrane transfer line is used to fluidically couple the laser ablation system with the ICP analysis system, replacing sample gases with a sweep gas via a PTFE membrane, ensuring continuous gas exchange without the need for physical clamps or restrictions, maintaining a stable plasma.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pinch valves are used to prevent atmospheric gas from entering the ICP torch, then plasma stability is improved, but device complexity and maintenance needs increase
Solution Approach 1:
The patent removes the pinch valve component from the system entirely and replaces it with a membrane-based gas exchange mechanism. The membrane allows selective gas permeation without requiring mechanical valves, thereby eliminating the complexity and maintenance needs associated with pinch valves while maintaining plasma stability.
Solution Approach 2:
The patent introduces a gas-permeable membrane as an intermediary between the sample transfer stream and the ICP torch. This membrane selectively allows certain gases to pass through while blocking others, providing plasma protection without the need for mechanical valve control systems.
2Reliability
If atmospheric gas is purged from the transfer line, then plasma extinguishment is prevented, but loss of time occurs during purging cycles
Solution Approach 1:
The gas-permeable membrane operates continuously to maintain the argon atmosphere in the transfer line, eliminating the need for periodic purging cycles. The membrane provides continuous selective gas exchange, allowing the plasma to remain stable without interruption and eliminating time losses associated with purge cycles.
Solution Approach 2:
The membrane pre-establishes the appropriate gas atmosphere in the transfer line before sample analysis begins, preventing atmospheric gas contamination from the outset. This preliminary gas exchange eliminates the need for subsequent purging operations during sample changeover.
3Ease of operation
If mechanical valves are used to control gas flow, then gas exchange is achieved, but mechanical failures and maintenance needs increase
Solution Approach 1:
The patent replaces the mechanical valve system with a membrane-based gas exchange system. The membrane uses passive diffusion and permeation principles to control gas flow without moving parts, eliminating mechanical failures while maintaining ease of gas flow control through selective permeability.
Solution Approach 2:
The gas-permeable membrane automatically regulates gas exchange based on the inherent properties of the membrane material and the pressure gradients present in the system. No external control mechanisms are needed, as the membrane self-regulates the gas flow to maintain the required atmosphere.
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 system effectively replaces over 99% of initial gases in the sample transfer stream with sweep gas, preventing plasma extinguishment and reducing mechanical failures, thereby enhancing sample throughput and reducing operational costs.
Implementation Method 1
a gas exchange membrane transfer line configured to replace gas in the sample transfer stream with sweep gas via gas exchange across a membrane of the gas exchange membrane transfer line
Implementation Method 2
ablating a portion of the target with one or more laser pulses to generate a plume containing particles and/or vapor ejected or otherwise generated from the target
Implementation Method 3
ICP spectrometry employs electromagnetically generated partially ionized argon plasma which reaches a temperature of approximately 7,000K
Implementation Method 4
the high temperature causes sample atoms to become ionized or emit light
Implementation Method 5
each chemical element produces a characteristic mass or emission spectrum, measuring the spectra of the emitted mass or light
Data Source
AI summary
Systems and methods are described for transferring gas from an ablation cell to an inductively coupled plasma analysis system via a gas exchange membrane transfer line to exchange gas introduced to the ablation cell with a sweep gas. A system embodiment includes, but is not limited to, a laser ablation cell configured to generate a sample transfer stream through laser ablation of a sample and introduction of a carrier gas to flow the ablated sample from the laser ablation cell; an inductively-coupled plasma analysis device configured to measure one or more analytes in the sample transfer stream; and a gas exchange membrane transfer line fluidically coupled between the laser ablation cell and the inductively-coupled plasma analysis device, the gas exchange membrane transfer line configured to replace gas in the sample transfer stream with sweep gas via gas exchange across a membrane of the gas exchange membrane transfer line.