Advantages of a small-volume counter-current chromatography column.

Counter-current chromatography (CCC) works with a support-free liquid stationary phase. This allows for preparative separations and purifications. However, there are serious technical constraints because of the need to keep a liquid stationary phase in a column. Centrifugal fields are used. A new commercial hydrodynamic 18mL column made with a narrow-bore 0.8mm Teflon tubing was evaluated by comparing it with older hydrodynamic CCC columns and a similar 19mL column but made with 1.6mm Teflon tubing. A small-volume CCC column allows for reliable and fast solute partition coefficient determination. When resolution is required, both high efficiency and liquid stationary phase retention are needed. Unfortunately, these two requirements bear technical contradictions. A column coiled with a narrow tubing bore will provide a high chromatographic efficiency while a column containing wider tubing bore will achieve higher stationary phase retention. In all cases, increasing the magnitude of the centrifugal field also increases the stationary phase retention. The solution is to build centrifuges able to produce high fields that will provide acceptable liquid phase retention with narrow-bore tubes. The new 18mL 0.8mm tubing bore column is able to rotate as fast as 2100rpm generating a 240xg field. The two older CCC columns cannot compete with the new one. However, the small 19mL column with 1.6mm bore tubing can be useful when fast results are desired without top resolution.