Sample Injector with Buffer Loop for LC
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Solution Overview
Problem
Current sample injectors for liquid chromatography face challenges in achieving high-throughput and flexibility in sample injection, particularly in adapting conditions like sample volume, flow rate, and pressure, while also minimizing carryover and dead volume, especially in high-pressure applications.
Innovation Solution
A sample injector design utilizing a single high-pressure LC switching valve, an aspiration/dispensing pump, and an analytical sample loop, which allows for flexible injection conditions, minimizes carryover, and reduces internal fluidic volumes, enabling fast and precise sample loading compatible with micro-LC systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple valves and pumps are used to increase flexibility in injection conditions, then adaptability is improved, but device complexity increases and productivity decreases
Solution Approach 1:
The single high-pressure LC switching valve is configured with multiple ports to perform multiple functions: sample injection, buffer loop switching, and washing operations. This multi-functional valve design eliminates the need for multiple dedicated valves and pumps, reducing device complexity while maintaining flexibility in injection conditions.
Solution Approach 2:
The system divides the fluidic path into distinct segments (sample loop, buffer loop, analytical loop) that can be independently controlled through the single switching valve. This segmentation allows flexible configuration of injection conditions without requiring additional valves, as each segment can be selectively activated based on operational requirements.
2Adaptability or versatility
If complex fluidic construction with multiple valves and pumps is used, then flexibility is improved, but washing efficiency decreases and carryover increases
Solution Approach 1:
The buffer loop is pre-filled with buffer solution before sample injection. This preliminary preparation allows for efficient washing of the sample loop between injections by simply switching the valve to redirect buffer flow through the sample loop, effectively removing carryover without requiring complex additional washing mechanisms.
Solution Approach 2:
The system maintains continuous buffer flow through the buffer loop during sample injection and analysis. This continuous circulation ensures that the buffer is always available for rapid washing of the sample loop between samples, maintaining low carryover without interrupting the analytical process or requiring additional washing pumps.
3Device complexity
If larger total sample volumes are used to compensate for increased dead volume, then compatibility with complex systems is improved, but loss of substance increases
Solution Approach 1:
The buffer loop is extracted as a separate, dedicated component with its own volume, distinct from the sample loop and analytical loop. This separation allows the dead volume of the buffer loop to be filled with inert buffer solution rather than sample, eliminating the need to increase sample volume to compensate for system dead volume, thus reducing sample consumption while maintaining compatibility with the system.
4Productivity
If faster sample loading is implemented to increase throughput, then productivity is improved, but manufacturing precision may be compromised
Solution Approach 1:
The system uses periodic switching of the high-pressure LC valve to control sample loading and injection timing. The valve switches between different configurations at precise intervals: first connecting the sample loop to the buffer loop for rapid buffer filling, then switching to connect the loaded sample loop to the analytical loop for injection. This periodic switching enables fast sample loading while maintaining precision through controlled timing.
Solution Approach 2:
The buffer loop acts as an intermediary between the sample introduction system and the analytical loop. It mediates the sample loading process by first receiving buffer to establish flow paths, then allowing rapid sample introduction without directly connecting the sample source to the analytical column. This intermediary buffer loop enables faster loading while maintaining precision by stabilizing the fluidic environment during the transition.
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 solution enables short injection cycle times, flexibility in adapting injection conditions, minimizes sample carryover, and reduces the total sample volume required, making it suitable for high-throughput and random-access liquid chromatography applications while maintaining precision and compatibility with micro-LC systems.
Implementation Method 1
The sample can be either drawn or pushed from a sample line into the sample loop by a dedicated pump, typically a syringe pump, also connected to the same valve generating negative and/or positive pressure
Implementation Method 2
The sample can be either drawn or pushed from a sample line into the sample loop by a dedicated pump, typically a syringe pump, also connected to the same valve generating negative and/or positive pressure
Data Source
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AI summary
A sample injector 100, 100' for liquid chromatography is disclosed comprising an LC switching valve 10 comprising a sample input port 11, an aspiration/dispensing pump port 12, an analytical sample loop input port 13 and an analytical sample loop output port 1), an LC pump port 15 and an LC column port 16, an aspiration pump fluidically 20, 21 connected to the aspiration/dispensing pump port 12 via a buffer sample loop 30 for aspirating a sample 1 into the buffer sample loop 30 when the aspiration/dispensing pump port 12 is connected to the sample input port 11, an analytical sample loop 40 connected to the LC switching valve 10 between the analytical sample loop input port 13 and the analytical sample loop output port 14, for receiving at least part of the sample 1 aspirated into the buffer sample loop 30 when the analytical sample loop input port 13 is connected to the aspiration/dispensing pump port 12, an LC column 50 fluidically connected to the LC column port 16, and an LC pump 60 fluidically connected to the LC pump port 15, for injecting the sample 1 received into the analytical sample loop 40 into the LC column 50 when the LC pump port 15 is fluidically connected to the analytical sample loop output port 14 and the LC column port 16 is fluidically connected to the analytical sample loop input port 13. A method of injecting a sample 1 for liquid chromatography by the sample injector 100, 100' is also disclosed. A liquid chromatography system 200 comprising the sample injector 100, 100' and a clinical diagnostic system 300 comprising the liquid chromatography system 200 are also disclosed.