Modeling of preparative closed-loop recycling liquid-liquid chromatography with specified duration of sample loading

The closed-loop recycling counter-current chromatography (CLR CCC) is performed in several consecutive separation stages. First, the loop is opened, and within a specified time the solution of solutes in the mobile phase is continuously fed to the column. After the solutes loading is finished, the loop is closed, and the first separation stage starts. After a certain number of cycles the first fraction of solutes is eluted, the loop is closed, and the second separation stage starts, and so on. In this study, simple equations are presented allowing the simulation of such separation processes. These equations can help to select a suitable compromise between the productivity and the resolution in the preparative and production CLR CCC separations. It is shown that the sample loading time about 20%-30% of the mean residence time is quite acceptable from the practical point of view: proper selection of the loading time and the recycling line length can allow increasing the productivity by an order of magnitude ensuring, a desirable separation.