Countercurrent chromatography approach to palladium and platinum separation using aqueous biphasic system

Intermittent sample loading technique as a tool for obtaining high- concentration elution bands in recycling liquid-liquid chromatography: Theoretical study of periodic and semi-continuous separation processes

To improve the efficiency of countercurrent chromatography (CCC) separations, we have previously proposed a new sample loading method called intermittent sample loading (ISL), in which continuous sample feed alternates with short periods of "clean" mobile phase feed to the CCC device. In semi-continuous separation processes, during sample feed periods, the sample is loaded in separate batches, each consisting of a series of intermittent sample loads. It was shown that the application of the intermittent sample loading method in the conventional isocratic CCC separations significantly increased process productivity and the concentration of compounds in the separated fractions. In this study, to further improve the CCC separations with intermittent sample loading, we discuss the application of the ISL method in the processes of close-loop recycling counter-current chromatography (CLR CCC). The advantage of the ISL CLR CCC over the ISL CCC is higher resolution and lower solvent consumption. Equations are presented that allow the simulation of periodic and semi-continuous ISL CLR CCC separations and the selection of optimal operational conditions for these separation processes. It is shown that the use of ISL technique in CLR CCC separations makes it possible to produce fractions of compounds with a much higher concentration than when using the conventional single sample loading method.

Closed-Loop Recycling Dual-Mode Counter-Current Chromatography with Specified Sample Loading Durations: Modeling of Preparative and Industrial-Scale Separations

We previously reported on a new counter-current chromatography (CCC) operating mode called closed-loop recycling dual-mode counter-current chromatography (CLR DM CCC), which incorporates the advantages of closed-loop recycling (CLR) and dual-mode (DM) counter-current chromatography and includes sequential separation of compounds in the closed-loop recycling mode with the mobile x-phase and in the inverted-phase counter-current mode with the mobile y-phase. The theoretical analysis of several implementations of this separation method was carried out under impulse sample injection conditions. This study is dedicated to the further development of CLR DM CCC theory applied to preparative and industrial separations, where high-throughput operation is required. Large sample volumes can be loaded via continuous loading within a specified time. To simulate CLR DM CCC separations with specified sample loading durations, equations are developed and presented in "Mathcad" software.