NOVEL DESIGN FOR CENTRIFUGAL COUNTERCURRENT CHROMATOGRAPHY: IV. FIGURE-8 COLUMN

Abstract

The toroidal columns using an equilateral triangular core, zigzag, and saw patterns has improved step by step both for retention of the stationary phase and peak resolution of the conventional toroidal coil in centrifugal countercurrent chromatography. To further improve the retention of stationary phase and peak resolution, a novel figure 8 toroidal coil was designed and the performance of the system was evaluated at various flow rates. In the figure-8 column with a capacity of 3 mL, the peak resolution of dipeptides (Val-Tyr and Trp-Tyr) was 1.63, and that of DNP-amino acids (DNP-DL-glu, DNP-β-ala, DNP-L-ala) were 1.92 and 1.85, respectively. The results indicated that retention of stationary phase and peak resolution were improved at lower flow rates. The Rs with lower mobile phase can be further increased by modifying the tubing to form a flat twisted configuration. With a decreased column length with a capacity of about 0.1 mL, resolution of the figure-8 column was 0.71 with about 40% retention of stationary phase at a flow rate of 0.005 mL/min.

Keywords:

• countercurrent chromatography
• dipeptide
• DNP-amino acid
• figure-8 column
• peak resolution
• retention of the stationary phase

Notes

Note: Flow rate: 0.05 mL/min; rotational speed: 1000 rpm.

^a Rs-a = Rs(V₁/V₂)^1/2, where Rs-a is the adjusted peak resolution and V indicates the column volume being specified by the subscript 1 for the standard plain column and 2 for the modified column.

Note: flow rate: 0.05 ml/min; rotational speed: 1000 rpm.

^a Rs-a = Rs(V₁/V₂)^1/2 = Rs(4.4/3)^1/2 = 1.21Rs.