Thermally Modulated Variable Restrictor for Chromatography Split Ratio
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Solution Overview
Problem
Chromatography systems with fixed restrictors face challenges in maintaining a constant split ratio during gradient separations due to changes in mobile phase density or composition, leading to non-linearity and inaccurate quantitation of peaks.
Innovation Solution
A thermally modulated variable restrictor is introduced to dynamically adjust the split ratio by controlling the temperature of the mobile phase stream, ensuring a constant split ratio throughout the chromatographic run by adjusting the heat exchange between the restrictor and the mobile phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed restrictor is used to split the mobile phase flow, then the system structure is simple and easy to operate, but the split ratio changes during gradient separations due to viscosity changes, leading to non-linearity and inaccurate quantitation
Solution Approach 1:
The patent applies a variable restrictor instead of a fixed restrictor, allowing the restriction to dynamically adjust during the chromatographic run. The restrictor's opening size changes in response to mobile phase conditions (viscosity, density, flow rate) to maintain a constant split ratio despite gradient changes, thereby resolving the contradiction between operational simplicity and quantitation accuracy.
Solution Approach 2:
The patent changes the physical parameters of the restrictor (opening size, restriction value) in response to changing mobile phase conditions. By monitoring parameters such as viscosity, density, or flow rate and adjusting the restrictor accordingly, the system maintains accurate split ratio control throughout gradient separations, eliminating the non-linearity problem while preserving ease of operation through automated control.
2Productivity
If the mobile phase density or composition is changed during gradient separations to improve peak capacity, then the separation performance is improved, but the viscosity changes cause the flow rate through the fixed restrictor to change, altering the split ratio
Solution Approach 1:
The patent implements a feedback control mechanism where the system monitors mobile phase conditions (density, viscosity, composition) during gradient separations and uses this information to adjust the variable restrictor. This feedback loop ensures that the split ratio remains stable despite changes in mobile phase properties, allowing gradient separations to maintain both high peak capacity and accurate quantitation.
Solution Approach 2:
The variable restrictor dynamically adapts its restriction value in response to changing mobile phase composition and density during gradient separations. This dynamic adjustment compensates for viscosity changes, maintaining a constant split ratio while allowing the gradient to proceed and improve peak capacity, thus resolving the contradiction between separation performance and split ratio stability.
3Manufacturing precision
If a thermally modulated variable restrictor is used to maintain constant split ratio, then the quantitation accuracy is improved, but the device complexity increases due to temperature control mechanisms
Solution Approach 1:
The patent replaces complex mechanical adjustment mechanisms with thermal modulation. By using temperature control to change the restrictor's physical properties (viscosity, density, opening size), the system achieves variable restriction with simpler control electronics rather than complex mechanical actuators, thereby reducing overall device complexity while maintaining high quantitation accuracy.
Solution Approach 2:
The patent utilizes thermal effects and phase transitions in the mobile phase or restrictor material to control flow restriction. By modulating temperature, the system changes the physical state or properties of the mobile phase/restrictor, achieving variable split ratio control through thermal means rather than complex mechanical systems, thus improving accuracy while managing device complexity.
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 solution maintains a consistent split ratio, preventing analyte precipitation and ensuring accurate quantitation of all peaks by maintaining an appreciable mobile phase density and optimizing the flow rate to the detector, even with changes in system pressure and mobile phase composition.
Implementation Method 1
a temperature element in thermal communication with said first mobile phase stream to exchange heat therewith
Implementation Method 2
Thermally modulated variable restrictor... dynamically adjusts a temperature setting of said temperature element... to adjust the heat exchange
Data Source
AI summary
A chromatography system includes a separation column that separates a sample carried by a compressible mobile phase flow into analytes and a splitter in fluidic communication with the separation column to receive and divide the compressible mobile phase flow into first and second mobile phase streams in accordance with a split ratio. A thermally modulated variable restrictor is coupled between the splitter and a detector. The restrictor receives the first mobile phase stream from the splitter and has a temperature element in thermal communication with the first mobile phase stream to exchange heat therewith. A controller, in communication with the restrictor, dynamically adjusts a temperature setting of the temperature element of the restrictor to adjust the heat exchange between the thermally modulated variable restrictor and the first mobile phase stream in order to keep the split ratio constant throughout a chromatographic run.