Liquid Chromatography Dwell Volume Determination via Pressure Trace
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Solution Overview
Problem
Current methods for determining the dwell volume of liquid chromatography systems are time-consuming, prone to contamination, and require physical reconfiguration, leading to inaccuracies and difficulties when transferring methods between systems with different dwell volumes.
Innovation Solution
A method that measures the system pressure response over time to determine the dwell volume by mixing solvents and adjusting their flow rates, eliminating the need for additional compounds or physical changes to the system, allowing for accurate dwell volume calculation without a UV tracer or column removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional UV tracer method is used to determine dwell volume, then measurement can be performed, but preparation time is increased and contamination risk arises
Solution Approach 1:
The patent extracts the dwell volume measurement process from the conventional UV tracer method by using the existing system pressure sensor to detect pressure changes caused by viscosity variations during gradient formation. This eliminates the need for additional UV tracer compounds and their associated preparation steps, directly resolving the technical contradiction between measurement capability and preparation time
Solution Approach 2:
The system uses its own built-in pressure sensor to perform dwell volume measurement without requiring external tracer compounds or additional equipment. The pressure changes during normal gradient operation are utilized for measurement, allowing the system to self-diagnose its dwell volume parameter without external intervention or contamination risk
2Measurement precision
If UV tracer compound is added to solvent, then dwell volume can be measured, but system contamination and performance degradation occur
Solution Approach 1:
The patent converts the natural viscosity differences between solvents in a gradient into a beneficial measurement signal. Instead of adding foreign tracer compounds, the method utilizes the inherent viscosity changes that occur during gradient formation, which naturally cause pressure variations detectable by the system's pressure sensor. This converts a physical property (viscosity) into a useful measurement signal without introducing contamination
Solution Approach 2:
The system pressure acts as an intermediary that translates the invisible viscosity changes during gradient formation into measurable pressure variations. The pressure sensor detects these changes, allowing dwell volume determination without direct contact between tracer compounds and the chromatographic system, thereby preventing contamination
3Adaptability or versatility
If dwell volume is not accurately determined, then method transfer between systems is difficult, but re-measurement requires system reconfiguration
Solution Approach 1:
The system automatically determines its own dwell volume parameter using its built-in pressure sensor and the pressure changes during gradient operation. This self-determination capability eliminates the need for manual reconfiguration or external tracer methods when transferring methods between systems, allowing operators to simply measure and input the dwell volume value without physical system changes
Solution Approach 2:
The patent changes the approach from physical system reconfiguration to parameter measurement and input. Instead of physically modifying the system to measure dwell volume, the method measures pressure parameter changes during gradient operation and calculates dwell volume from these data, allowing easy transfer between systems through software parameter adjustment rather than physical reconfiguration
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 approach reduces preparation time, minimizes contamination risk, and enhances accuracy, facilitating method transfer between different chromatography systems by directly calculating dwell volume from pressure traces without requiring additional tubing or column knowledge.
Implementation Method 1
A system pressure of the liquid chromatography system is measured to determine a pressure trace defined as the measured system pressure as a function of time
Implementation Method 2
The solvent mixture may have a viscosity that changes in response to the gradient composition. The change in viscosity may be substantially linearly proportional to a change in the solvent mixture according to the gradient composition
Data Source
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AI summary
Described is a method for determining a dwell volume of a liquid chromatography system and a liquid chromatography system that can determined the system dwell volume. The method includes mixing a flow of a first solvent with a flow of a second solvent to form a solvent mixture. The flows of the first and second solvents are decreased and increased, respectively, to generate a gradient composition. A system pressure of the liquid chromatography system is measured to determine a pressure trace defined as the measured system pressure as a function of time. The dwell volume of the system is determined from a time delay determined between the gradient composition at the mixing location and the pressure trace. The method can be performed with a liquid chromatography system having a chromatographic column or a flow restrictor used in place of the chromatographic column.