Sample Introduction Channel Switching for GC Purging
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Solution Overview
Problem
In thermal desorption type sample introduction devices for gas chromatographs, the sample introduction channel is not thoroughly purged, leading to residual sample components from previous measurements affecting subsequent analyses due to dead-end configurations, especially when dealing with high boiling point components.
Innovation Solution
A sample introduction device with a channel configuration that includes a splitter with two outlets, where the second carrier gas supply channel allows carrier gas to flow through the sample introduction channel during the trap capture process, preventing dead-end sections and ensuring thorough purging by connecting the sample introduction channel to the second split outlet during the recapture process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If the sample introduction channel is configured with dead-end sections to enable recapture of sample components, then sample components can be recaptured and reused, but the channel is not thoroughly purged and residual sample components from previous measurements interfere with subsequent analyses
Solution Approach 1:
The patent applies dynamics by making the channel configuration changeable through valve control. The system dynamically switches between recapture mode (with dead-end configuration) and purging mode (with through-flow configuration), allowing the same channel to serve different functions at different times, thus resolving the contradiction between recapture capability and purging effectiveness
Solution Approach 2:
The patent implements periodic action by alternating between recapture operations and purging operations in a cyclic manner. After sample recapture is completed, the system periodically performs purging by reversing the carrier gas flow direction, ensuring that residual samples are removed before the next measurement, thus maintaining measurement accuracy while preserving recapture functionality
2Quantity of substance
If carrier gas flow is stopped in the sample introduction channel during trap capture to enable recapture, then sample components can be retained, but thorough purging cannot be achieved
Solution Approach 1:
The patent applies inversion by reversing the carrier gas flow direction to achieve purging. Instead of flowing gas from the trap toward the sample tube (which would not purge dead-end sections), the system reverses the flow to move from the sample tube side toward the trap, effectively flushing out residual samples from all channel sections including dead-ends, thus achieving thorough purging while maintaining the ability to retain samples during capture
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 configuration prevents residual sample components from previous measurements from interfering with current analyses by ensuring thorough purging of the sample introduction channel, enhancing measurement accuracy and reliability.
Implementation Method 1
a thermal desorption type sample introduction device in which a sample tube filled with an adsorbent and a solid sample is heated to cause desorption of a gaseous sample
Implementation Method 2
a gas containing the sample components desorbed from the sample tube is passed through the cooled trap to cause adsorption of the components onto the trap
Implementation Method 3
the trap is heated to again desorb the sample components and introduce them into the analytical column
Data Source
AI summary
A sample introduction device having a channel configuration which allows recapture of samples and in which thorough purging is performed so that no sample components remain inside the channel. In the trap capture process, a first six-way switching valve is placed in state where ports a-f, b-c and d-e are connected, a second six-way switching valve is placed in state where ports a-b, c-d and e-f are connected, and an electromagnetic valve is opened. Carrier gas is introduced through a carrier gas channel, and is discharged via the first six-way valve-sample channel-second six-way switching valve-trap channel-second six-way switching valve-channel-first six-way valve-discharge channel. Carrier gas is also introduced through the path going through the electronic control flow controller, so the operation of stabilization of the analysis channel continues to be performed.