Autosampler Switching Valve for Liquid Chromatography
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In liquid chromatography with autosamplers using the total-volume injection method, the time between the end of analyzing one sample and starting the next is prolonged due to the need to reset the mobile phase components in all channels, including the sample loop, before the next analysis can begin, as the needle cannot be removed from the injection port during this process.
Innovation Solution
An autosampler with a switching valve that includes injecting, purging, and loading positions allows for separate replacement of the mobile phase in the sampling channel, enabling higher flow rates and quicker phase changes, allowing the needle to be withdrawn and the next sample to be collected while the analysis channel is being purged.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the mobile phase components in all channels including the sample loop are returned to the state before gradient start by delivering a mobile phase through the sample loop while the needle is inserted in the injection port, then the separation performance is maintained, but the time from the end of analysis to when the next sample can be started is prolonged
Solution Approach 1:
The patent divides the mobile phase replacement process into two separate segments: (1) replacement in the sampling channel while the needle is in the injection port, and (2) replacement in the analysis channel after the needle is removed. This segmentation allows the sampling channel to be purged at high flow rate without being blocked by the needle, reducing the overall time while maintaining separation performance in the analysis channel.
Solution Approach 2:
The patent performs the mobile phase replacement in the sampling channel as a preliminary action before removing the needle from the injection port. By using the purging position to replace the mobile phase in the sampling channel first, the system prepares the sampling pathway for the next injection without delaying the needle removal, thus reducing the idle time between analyses.
2Reliability
If the needle is kept inserted in the injection port during the mobile phase replacement process, then the sample loop is properly purged, but the needle cannot be pulled out to collect the next sample
Solution Approach 1:
The patent introduces a dynamic switching mechanism with multiple positions (purging position and loading position) that allows the system to change the needle's functional state. In the purging position, the needle remains inserted for proper sample loop purging. After purging is complete, the system dynamically transitions to the loading position where the needle is removed from the injection port, enabling immediate collection of the next sample. This dynamic switching resolves the contradiction between maintaining purging reliability and improving sample collection efficiency.
Solution Approach 2:
The patent temporarily discards the needle-injection port connection during the purging phase to enable high-speed mobile phase replacement, then recovers the connection in the loading position for sample collection. The switching valve allows the system to discard the needle connection when it hinders purging efficiency, and recover it when needed for sample injection, thus optimizing both purging reliability and productivity.
3Speed
If the mobile phase is delivered at a high flow rate through the sampling channel, then the replacement is swift, but the channel resistance must be considered
Solution Approach 1:
The patent segments the fluid pathway into the sampling channel and the analysis channel, allowing different flow rates to be applied to each. The sampling channel, which has lower resistance, can operate at high flow rates for swift mobile phase replacement. The analysis channel, which has higher resistance due to the analytical column, operates at appropriate lower flow rates to maintain separation performance. This segmentation resolves the contradiction between speed and pressure by allowing optimized flow conditions in each segment.
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 reduces the time from the end of one analysis to the start of the next by enabling swift mobile phase replacement in the sampling channel and simultaneous sampling of the next sample during the analysis channel's purge process, thereby decreasing the overall time required for successive sample analysis.
Implementation Method 1
a switching valve (12). The switching valve (12) includes a delivery port (6) to which a delivery device (2) for delivering a mobile phase is connected, a sampling port (1) to which a base end of a sampling channel (14) is connected, an injection port (4) that is connected to the sampling channel (14) by insertion of a tip of a needle (15)
Implementation Method 2
a sampling channel (14) including, at a tip, a movable needle (15) for performing suction and discharge of a sample
Implementation Method 3
a sample loop (16) for retaining a liquid taken in from the needle tip
Implementation Method 4
a delivery device (2) for supplying a mobile phase to the analysis channel (22)
Implementation Method 5
an analysis channel (22) including an analytical column (24) for separating a sample into components
Data Source
AI summary
An autosampler according to an embodiment includes a sampling channel including a movable needle at a tip, and a switching valve, including a plurality of ports, for switching the connection state between the ports by switching the position of a rotor by rotating the rotor. The rotor of the switching valve includes an injecting position in which a delivery port and a sampling port are communicated and an injection port and an analysis port are communicated, a purging position in which the delivery port and the sampling port are communicated and the injection port and a drain port are communicated, and a loading position in which the delivery port and the analysis port are communicated.