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Keywords = redosing of the stationary phase

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14 pages, 4786 KB  
Article
Optimizing Chromatographic Separation with Redosing: Effects on Separation Efficiency of a Model System in Centrifugal Partition Chromatography
by Felix Buthmann, Jan Hohlmann, Mareen Neuwald and Gerhard Schembecker
Separations 2024, 11(4), 111; https://doi.org/10.3390/separations11040111 - 3 Apr 2024
Cited by 4 | Viewed by 3266
Abstract
This study investigates and optimizes chromatographic separation in a Centrifugal Partition Chromatograph. Therefore, a model system is separated in a single-disc rotor. The occurring loss of the stationary phase lowers the separation efficiency over time. We introduced a new mode of operation, called [...] Read more.
This study investigates and optimizes chromatographic separation in a Centrifugal Partition Chromatograph. Therefore, a model system is separated in a single-disc rotor. The occurring loss of the stationary phase lowers the separation efficiency over time. We introduced a new mode of operation, called the redosing of the stationary phase, to counteract this hydrodynamic phenomenon. Experiments with redosing at an optimized operating point demonstrate almost constant separation performance over 12 h, reducing solvent consumption by 45% and increasing chromatographic resolution by 37%. The improvement in retention by 69% contributes to this enhancement. Accordingly, reference experiments without redosing were conducted as a benchmark, highlighting the automated mode’s benefits, as mentioned. Full article
(This article belongs to the Section Chromatographic Separations)
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19 pages, 16411 KB  
Article
Counteracting Bleeding in Centrifugal Partition Chromatography: Redosing of the Stationary Phase
by Felix Buthmann, Jan Hohlmann, Sophia Volpert, Mareen Neuwald, Djamal Hamza and Gerhard Schembecker
Separations 2024, 11(4), 98; https://doi.org/10.3390/separations11040098 - 27 Mar 2024
Cited by 6 | Viewed by 2063
Abstract
Centrifugal Partition Chromatography is a type of Liquid-Liquid Chromatography that offers several advantages compared to Liquid Chromatography. Two immiscible liquids are utilized, and one phase has to be immobilized to implement chromatographic separation. This is performed with the help of centrifugal force. As [...] Read more.
Centrifugal Partition Chromatography is a type of Liquid-Liquid Chromatography that offers several advantages compared to Liquid Chromatography. Two immiscible liquids are utilized, and one phase has to be immobilized to implement chromatographic separation. This is performed with the help of centrifugal force. As this immobilization is not ideal, the stationary phase continuously leaks out of the apparatus (so-called bleeding). We measured the stationary phase’s loss precisely and implemented a controller to compensate for it during operation. This innovative mode of operation is called redosing of the stationary phase and prolongs the experimental runtime significantly. In a first step, we implemented an open-loop controller, which was capable of counteracting bleeding but could not dial to a given setpoint precisely. Therefore, a closed-loop controller with a moving frame shifting factor was programmed. This controller reached and maintained setpoints with high accuracy. The last experimental step was to check for boundaries of this new degree of freedom. In addition, we highlighted the accompanying hydrodynamics during redosing with the help of Computational Fluid Dynamics. We were able to show the influence of different volumes of the redosed stationary phase on the flow regime. Full article
(This article belongs to the Section Chromatographic Separations)
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17 pages, 7327 KB  
Article
Prediction of Bleeding via Simulation of Hydrodynamics in Centrifugal Partition Chromatography
by Felix Buthmann, Sophia Volpert, Jörg Koop and Gerhard Schembecker
Separations 2024, 11(1), 16; https://doi.org/10.3390/separations11010016 - 3 Jan 2024
Cited by 6 | Viewed by 2866
Abstract
Centrifugal Partition Chromatography (CPC) utilizes a two-phase liquid–liquid system as mobile and stationary phases. During operation, the latter continuously drains out of the rotor, despite it being in fact stationary, leading to decreasing separation efficiency over time, a phenomenon still poorly understood today [...] Read more.
Centrifugal Partition Chromatography (CPC) utilizes a two-phase liquid–liquid system as mobile and stationary phases. During operation, the latter continuously drains out of the rotor, despite it being in fact stationary, leading to decreasing separation efficiency over time, a phenomenon still poorly understood today because neither simulations nor extensive experimental investigations have addressed this so-called bleeding. With the model presented in this study, the underlying hydrodynamics are discussed in detail. This model can simulate bleeding over 60 s and is verified experimentally for different operating points (volumetric flow rates of 5, 12, and 20 mL⋅min−1) of the Centrifugal Partition Chromatograph utilizing an aqueous–organic phase system. We simulated two interconnected chambers at the rotor inlet and analyzed the loss of the stationary phase over time. The results of the simulated second chamber are closely aligned with the experimental validation results. Thus, the prediction of bleeding utilizing the simulation of hydrodynamics was successful. Moreover, we highlighted the benefits of the two-chamber setup modeled in this study compared to single-chamber models. Full article
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