Chromatographic Method Transfer Using Compressible Fluid Pressure Correction
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Solution Overview
Problem
Transferring carbon dioxide-based chromatography separation methods between different chromatographic systems is challenging due to variations in average mobile phase density and pressure, which affect retention characteristics and selectivity, and existing methods may not accurately account for extracolumn pressure drops.
Innovation Solution
A method involving identifying average system and column pressures, calculating elution time differentials, and using correction coefficients to adjust parameters in the target system, along with lookup tables for tubing pressure drops, to maintain chromatographic integrity by matching average column pressures across systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If average system pressure is used to estimate average column pressure, then method transfer between systems is simplified, but extracolumn pressure drops skew the estimation and reduce accuracy
Solution Approach 1:
The patent segments the pressure measurement approach by introducing separate measurements for system pressure and column pressure, and by creating correction factors that account for extracolumn pressure drops. This segmentation allows the system to maintain simplicity while improving accuracy through targeted corrections.
Solution Approach 2:
The patent introduces correction factors as intermediaries between the measured system pressure and the actual column pressure. These correction factors act as mediators that compensate for extracolumn pressure drops, allowing accurate column pressure estimation without direct measurement inside the column.
2Adaptability or versatility
If separation method is transferred between different chromatographic systems, then system versatility is improved, but retention characteristics and selectivity may change due to density and pressure variations
Solution Approach 1:
The patent focuses on maintaining critical parameters (average column pressure and mobile phase density) consistent across different systems. By identifying and controlling these key parameters, the method ensures reliable retention characteristics and selectivity while allowing transfer between different chromatographic systems.
Solution Approach 2:
The patent implements a feedback mechanism where correction factors are calculated based on system characteristics and used to adjust pressure estimates in transferred methods. This feedback loop ensures that retention characteristics remain consistent even when transferring between systems with different extracolumn pressure drops.
3Reliability
If extensive experimentation is performed to develop and optimize separation methods, then separation quality is improved, but development time and complexity increase
Solution Approach 1:
The patent performs preliminary characterization of system pressure drops and calculates correction factors before method transfer. This preliminary action eliminates the need for extensive re-optimization when transferring methods between systems, significantly reducing development time while maintaining separation quality.
Solution Approach 2:
The patent creates a corrected pressure profile copy from the original system that accounts for extracolumn pressure drops. This copied and corrected method can be directly applied to the target system, reducing the need for extensive experimentation while preserving separation quality.
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 enables efficient transfer of carbon dioxide-based separations by minimizing differences in retention factors and selectivity between systems, ensuring chromatographic integrity is preserved, with retention factor differences less than 10% and selectivity changes less than 5%.
Implementation Method 1
chromatographic separations using a mobile phase comprising carbon dioxide
Implementation Method 2
carbon dioxide based chromatography system
Implementation Method 3
pressure drops outside the column of a chromatographic system may skew an estimation of an average column pressure
Implementation Method 4
pressure profile
Data Source
AI summary
Methods for transferring a carbon dioxide based separation procedure from a reference chromatographic system to a target chromatographic system involve alternative techniques for determining system pressure drops not attributable to the column. One technique involves leveraging experimental chromatography to develop a correction factor that is a function of at least one correction coefficient and at least one ratio of the differential analyte retention time to the retention time in the reference system. Another technique involves leveraging other experimental measurements of tubing pressure drops under various condition to develop a lookup table that can be used to identify likely tubing pressure drops in the target system. A third technique leverages knowledge of the separation procedure and the target system and the likely nature of the relevant flow to calculate tubing pressure drops in the target system.