Capability of the toroidal coil centrifuge investigated for performing countercurrent chromatography (CCC): (1) Mass transfer rates of protein molecules through the interface were studied using a simple rotary device which carries 5 test tube holders symmetrically around the rotary shaft. Each experiment was initiated by introducing two immiscible solvent phases to each test tube, first delivering 2 ml of the lower phase containing the test sample over which 2 ml of the upper layer free of sample was gently layered. Then a set of the tube holders was rotated at 30 rpm around the central axis inclined at 18 degrees from the horizontal line. At various intervals, the rotation was stopped and an aliquot (50 microl) of each phase was pipetted to measure the amount of sample transferred through the interface. The results clearly indicated that the mass transfer rate was negatively correlated to the molecular weight of the analytes as follows: human serum albumin (Mw 68,000), .00002 cm/sec; ovalbumin (Mw 45,000), .000025 cm/sec; lysozyme (Mw 14,000), .000035 cm/sec; and methylene blue (Mw 374), .000065 cm/sec; and potassium dichromate (Mw 294), .000255 cm/sec. These results are consistent with the effects of the Coriolis force on the partition efficiency reported last year. (2) In order to improve the performance of the toroidal coil CCC system, a new compact table top unit was designed and determined the optimal experimental conditions using a two-phase solvent system composed of chloroform/acetic acid/0.1M HCl and a set of DNP-amino acids as test samples. Using a 0.4mm ID toroidal coil, a series of experiments were performed to study the effects of various parameters (including flow rate and elution mode of the mobile phase, revolution speed, column length and sample volume) on the partition efficiency. A maximum partition efficiency of over 10,000 theoretical plates was achieved from a long toroidal coil prepared from 120 m of teflon tubing with a total capacity of about 15 ml. We are planning to apply these optimum conditions for separating various proteins.
