2D-LC Pressure Control via Fluidic Valve and Dynamic Flow
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Solution Overview
Problem
Conventional sample separation systems in liquid chromatography face challenges in maintaining consistent pressure and flow rates, leading to mechanical stress and potential deterioration of separation units, especially during steep gradients in two-dimensional liquid chromatography (2D-LC) where frequent and rapid viscosity changes occur.
Innovation Solution
A sample separation apparatus and method that maintain a constant pressure at a predefined position between two separation units, allowing for variable flow rates while controlling pressure through fluid drives and a fluidic valve, thereby reducing mechanical stress and extending the lifespan of separation units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If variable flow rates are used during steep gradients in 2D-LC, then separation efficiency is improved, but pressure instability and mechanical stress on separation units increase
Solution Approach 1:
The system dynamically adjusts the flow rate of the mobile phase during the separation process, particularly during steep gradients in 2D-LC. The control unit modifies flow parameters in real-time based on separation requirements, allowing high flow rates during gradient changes for efficiency while maintaining pressure stability through active control, thus resolving the contradiction between productivity and reliability
Solution Approach 2:
The system incorporates pressure sensors and control units that continuously monitor pressure conditions and provide feedback to adjust flow rates. This closed-loop control ensures that pressure remains stable even when flow rates vary during separation, addressing the contradiction by using feedback mechanisms to maintain reliability while enabling productivity improvements through variable flow
2Reliability
If constant flow rate is maintained during gradient separation, then pressure stability is improved, but separation efficiency during steep gradients deteriorates
Solution Approach 1:
The system transitions from static constant flow rate control to dynamic flow rate adjustment. The control unit enables the flow rate to vary during different phases of the gradient separation, maintaining constant flow during isocratic conditions for pressure stability while allowing variable flow during gradient transitions for improved separation efficiency, thus resolving the contradiction
3Productivity
If high flow rates are used to reduce analysis time, then productivity is improved, but mechanical stress and deterioration of separation units increase
Solution Approach 1:
The system employs periodic modulation of flow rates rather than continuously high flow rates. During gradient transitions, flow rates are temporarily increased to maintain separation efficiency and reduce analysis time, then reduced during isocratic phases to minimize mechanical stress on separation units. This periodic action pattern resolves the contradiction between productivity and separation unit lifespan by alternating between high and low flow states
Solution Approach 2:
The control unit pre-adjusts flow rates before gradient transitions to prevent sudden pressure spikes that would cause mechanical stress. By anticipating gradient changes and smoothly modulating flow rates in advance, the system maintains high productivity during separations while protecting separation units from deterioration through cushioned transitions
Data Source
AI summary
A sample separation apparatus for separating a liquid sample includes a first separation unit for separating the sample, a first fluid drive for conducting the sample to be separated through the first separation unit, a second separation unit, arranged downstream of the first separation unit, for further separating the sample, a second fluid drive for at least partially conducting the sample through the second separation unit, and a fluidic valve having interfaces fluidically coupled to the first and second fluid drives and being switchable for performing the separation of the sample. The apparatus is configured for adjusting a pressure at a predefined position to a predefined value, wherein the predefined position is in a fluidic path between an outlet of the first separation unit and an inlet of the second separation unit or in fluid communication with this fluidic path.