Practical Approach to the Creation of a Concentration Gradient in a Stationary Phase Retained in a Rotating Coiled Column

Abstract

Countercurrent chromatography (CCC) works with a liquid stationary phase. It is proposed to create a concentration gradient in the stationary phase during the chromatographic run. The gradient concentration is initiated putting a known volume of neat stationary phase at the head of the CCC column and a known volume of dithizone (a test die) concentrated stationary phase at the end of the CCC column. Water‐organic solvent biphasic liquid systems were tested. The aqueous phase is the mobile phase. Hexane, decane, chloroform, methylisobutyl ketone, tetrachloromethane, or ethyl acetate were used as the dithizone containing stationary phase. It was found that the concentration gradient created inside the column is dependent on the operational hydrodynamic parameters and physicochemical properties of two‐phase liquid systems used. The water‐organic solvent liquid systems were divided into two types: 1. “Nimble” (easily mixed) systems that readily form concentration gradients, which can be completely leveled with time; 2. “Reluctant” (difficult to mix) systems that do not form a gradient.