Online Virial Coefficient Method for Macromolecule Characterization
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Solution Overview
Problem
Current methods for determining virial coefficients in light scattering measurements require large sample volumes, are prone to errors due to inter-detector broadening, and involve time-consuming dialysis processes, especially when measuring cross-virial coefficients between different molecular species.
Innovation Solution
The Online Virial Coefficient Method involves a series of injections at different concentrations, using either the injection valve or dual-pump methods to minimize sample quantities and automate the process, allowing for direct calculation of molecular characteristics like weight-averaged molar mass, mean square radius, and virial coefficients, while integrating signals to account for dilution and broadening effects, and optionally incorporating in-line dialysis for buffer control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the standard plateau method is used to determine virial coefficients, then measurement accuracy is maintained, but large sample volumes (1-3 mL) are required
Solution Approach 1:
The patent replaces the mechanical plateau method with an online light scattering method that continuously monitors sample properties during elution. Instead of requiring complete saturation of flow cells, the system uses detectors to measure light scattering and concentration in real-time, allowing determination of virial coefficients from the elution profile rather than from saturated plateau conditions.
Solution Approach 2:
The patent introduces an online light scattering detector and concentration detector as intermediaries between the sample injection and the measurement process. These detectors continuously monitor the sample properties during elution, providing real-time data that can be used to calculate virial coefficients without requiring the sample to reach plateau conditions in the flow cell.
2Measurement precision
If multiple detectors are used in series to measure light scattering, then molecular characteristics can be determined, but inter-detector broadening causes measurement errors
Solution Approach 1:
The patent uses the concentration detector as a feedback reference to correct for inter-detector broadening effects. By continuously monitoring the concentration profile and using it to normalize the light scattering measurements, the system compensates for the broadening that occurs as the sample elutes through the detector series, thereby maintaining measurement accuracy.
3Loss of information
If cross-virial coefficients between different molecular species are measured, then interaction information is obtained, but the process becomes more complex and time-consuming
Solution Approach 1:
The patent creates a universal measurement system that can determine both self-virial coefficients and cross-virial coefficients using the same online light scattering and concentration detection methodology. The system processes different molecular species simultaneously through the elution profile, applying the same mathematical framework to extract both self-interaction and cross-interaction parameters without requiring separate measurement protocols.
4Measurement precision
If dialysis is performed to control buffer conditions, then measurement accuracy is improved, but the process becomes time-consuming
Solution Approach 1:
The patent performs dialysis as a preliminary action before the online measurement process. By completing the buffer exchange and equilibration beforehand, the sample is pre-conditioned to the required buffer conditions, allowing the subsequent light scattering measurements to proceed without further dialysis steps during the actual measurement process.
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 method reduces sample requirements, improves accuracy by eliminating inter-detector broadening effects, and automates the measurement process, enabling precise determination of virial coefficients with minimal sample usage and streamlined dialysis, enhancing the efficiency of molecular characterization.
Implementation Method 1
The light scattered from a small volume of the solution is measured over a range of angles
Implementation Method 2
acquiring the scattered intensity at each angle by means of a photodetector
Data Source
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AI summary
A new method is presented for measuring the molecular properties of an unfractionated solution of macromolecules. Sample aliquots spanning a range of concentrations are injected sequentially into a stream of solution and flow towards the detectors. Each aliquot produces, thereby, an effective "peak" whose elements correspond to different concentrations of the diluted aliquot. The weight averaged molar mass, the mean square radius, and the second virial coefficient of the macromolecules in solution are derived from an analysis of the angular and concentration dependence of the scattering signals throughout the corresponding peaks. In contrast to earlier on-line methods, better accuracy is achieved, while using a smaller quantity of sample. A similar method for determining cross virial coefficients between two distinct species of macromolecules is also presented.