A model for continuous sample feed and separation with counter‐current chromatography based on elution‐extrusion mode and its application

A novel and meaningful theoretical model was established with counter-current chromatography based on the elution-extrusion mode for efficient continuous separation. For the experimental verification of the theory, the separation of the binary mixture luteolin/baicalein was studied. The velocity model and volume model of the chromatographic separation behavior of the target compounds in the separation process were given by theoretical analysis. The results showed that this method had obvious advantages in the separation of binary mixtures. In addition, the established model was used to predict and isolate oleuropein from olive leaves. A two-phase solvent system of n-butanol/ethyl acetate/methanol/water (1:19:1:19, v/v/v/v) was chosen for the continuous separation of oleuropein. After optimizing the conditions in this way, a large amount of sample loading was achieved; the volume of injections can reach 48 ml, approximately 35.29% of the volume of the counter-current chromatography column, and oleuropein with a purity of 86.42% was obtained within 80 min. The model provided technical support for the prediction of chromatographic behavior and operating parameters during continuous separation and preparation of counter-current chromatography. It has great application prospects and significance in separation preparation, especially in large-scale industrial preparation.