Efforts have been successfully made to improve a preparative CCC scheme utilizing a slowly rotating coil assembly by optimizing the orientation of the coiled column. By the aid of a standard set of test samples and a two-phase solvent system, the performance of the single coil was examined in both eccentric and coaxial orientations with respect to the axis of rotation. In the eccentric location 10 cm away from the rotation axis, changes in the skew angle and/or inclination of the apparatus failed to improve the separation significantly. On the other hand, the coils mounted coaxially around the rotation axis in various helical diameters all produced excellent peak resolution at critical rotational speeds due to a high level of stationary phase retention. This finding facilitated the development of a new separation column consisting of multiple layers of the coil coaxially arranged around the rotary support. The preparative capability of this multi-layer coil was demonstrated in the separations of lg-quantity samples with satisfactory results. The present scheme is amenable to be further scaled up for industrial applications.
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