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Exploitation of temperature and solvent gradients in preparative liquid chromatography
Despite chromatography has become a relatively mature separation technology, progress has never stopped, e.g. via exploiting new degrees of freedom to improve performance and cost-effectiveness. Among them, gradients are considered as attractive options to deal with difficult separation problems when normal approaches are not able to meet desired performance. Owing to simplicity and controllability, solvent gradients are widely used in liquid chromatography and temperature gradients in gas chromatography. However, the potential of applying temperature gradients in liquid chromatography has not been fully explored. This work focuses on theoretical design and experimental validation of temperature and solvent gradients in preparative liquid chromatography followed by an evaluation of the potential for gradient combinations. A ternary separation characterised by a relative wide retention time spectrum was chosen as the model problem. In this scenario, a component falls behind in the chromatogram compared to the other two components, which leads to a rather long cycle time connected with a low productivity. By applying gradients, migration velocities of components can be individually manipulated in order to reduce this long cycle time and, thus, to increase the productivity. In this study, a rapid and general design tool for gradients based on equilibrium theory was utilised to generate graphical solutions. Space-time diagrams illustrate migration paths of components under the isocratic/isothermal conditions and influence of gradients. These paths are governed by thermodynamics and can be quantified by adsorption isotherms. As a key information, characteristic times can be identified for gradients to be applied in the repetitive batch chromatography mode. These specific switch times are crucial to optimise the separation regimes to reduce the cycle time. In the first part, isotherm parameters of the three components of a model system were determined focusing on the linear range for certain ranges of temperatures and ...
Exploitation of temperature and solvent gradients in preparative liquid chromatography
Despite chromatography has become a relatively mature separation technology, progress has never stopped, e.g. via exploiting new degrees of freedom to improve performance and cost-effectiveness. Among them, gradients are considered as attractive options to deal with difficult separation problems when normal approaches are not able to meet desired performance. Owing to simplicity and controllability, solvent gradients are widely used in liquid chromatography and temperature gradients in gas chromatography. However, the potential of applying temperature gradients in liquid chromatography has not been fully explored. This work focuses on theoretical design and experimental validation of temperature and solvent gradients in preparative liquid chromatography followed by an evaluation of the potential for gradient combinations. A ternary separation characterised by a relative wide retention time spectrum was chosen as the model problem. In this scenario, a component falls behind in the chromatogram compared to the other two components, which leads to a rather long cycle time connected with a low productivity. By applying gradients, migration velocities of components can be individually manipulated in order to reduce this long cycle time and, thus, to increase the productivity. In this study, a rapid and general design tool for gradients based on equilibrium theory was utilised to generate graphical solutions. Space-time diagrams illustrate migration paths of components under the isocratic/isothermal conditions and influence of gradients. These paths are governed by thermodynamics and can be quantified by adsorption isotherms. As a key information, characteristic times can be identified for gradients to be applied in the repetitive batch chromatography mode. These specific switch times are crucial to optimise the separation regimes to reduce the cycle time. In the first part, isotherm parameters of the three components of a model system were determined focusing on the linear range for certain ranges of temperatures and ...
Exploitation of temperature and solvent gradients in preparative liquid chromatography
An, Xinghai (author) / Hamel, Christof
2023-01-01
Theses
Electronic Resource
English
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