Comparison of the peak resolution and the stationary phase retention between the satellite and the planetary motions using the coil satellite centrifuge with counter-current chromatographic separation of 4-methylumbelliferyl sugar derivatives

Abstract

Coil satellite centrifuge (CSC) produces the complex satellite motion consisting of the triplicate rotation of the coiled column around three axes including the sun axis (the angular velocity, ω1), the planet axis (ω2) and the satellite axis (the central axis of the column) (ω3) according to the following formula: ω1 = ω2 + ω3. Improved peak resolution in the separation of 4-methylumbelliferyl sugar derivatives was achieved using the conventional multilayer coiled columns with ethyl acetate/1-butanol/water (3 : 2 : 5, v/v) for the lower mobile phase at the combination of the rotation speeds (ω1, ω2, ω3) = (300, 150, 150 rpm), and (1 : 4 : 5, v/v) for the upper mobile phase at (300 : 100 : 200 rpm). The effect of the satellite motion on the peak resolution and the stationary phase retention was evaluated by each CSC separation with the different rotation speeds of ω2 and ω3 under the constant revolution speed at ω1 = 300 rpm. With the lower mobile phase, almost constant peak resolution and stationary phase retention were yielded regardless of the change of ω2 and ω3, while with the upper mobile phase these two values were sensitively varied according to the different combination of ω2 and ω3. For example, when ω2 = 147 or 200 rpm is used, no stationary phase was retained in the coiled column while ω2 = 150 rpm could retain enough volume of stationary phase for separation. On the other hand, the combined rotation speeds at (ω1, ω2, ω3) = (300, 300, 0 rpm) or (300, 0, 300 rpm) produced insufficient peak resolution regardless of the choice of the mobile phase apparently due to the lack of rotation speed except at (300, 0, 300 rpm) with the upper mobile phase. At lower rotation speed of ω1 = 300 rpm, better peak resolution and stationary phase retention were obtained by the satellite motion (ω3) than by the planetary motion (ω2), or ω3 > ω2. The effect of the hydrophobicity of the two-phase solvent systems on the stationary phase retention was further examined using the n-hexane/ethyl acetate/1-butanol/methanol/water system at different volume ratios. In the satellite motion at (ω1, ω2, ω3) = (300, 150, 150 rpm), almost constant stationary phase retention was obtained with the lower mobile phase regardless of the hydrophobicity of the solvent system whereas the stationary phase retention varied according to the volume ratio of the two-phase solvent system for the upper mobile phase. However, stable stationary phase retention was observed with either phase used as the mobile phase. In order to analyze the acceleration acting on the coiled column, an acceleration sensor was set on the column holder by displacing the multilayer column. The combination of the rotation speeds at (300, 100, 200 rpm) showed double loops in the acceleration track, whereas (300, 150, 150 rpm) showed a single loop, and all other combinations showed, complex tracks. The overall results indicate that the satellite motion is seriously affected by the combination of rotation speeds and the hydrophobicity of the two-phase solvent system when the up...

Partition efficiencies of three different coiled columns for the coil satellite centrifuge at higher rotation speed combinations

“…On the other hand, in the rotation speed combination types III and IV, extremely low stationary phase retention was obtained even by increasing the revolution speed. This tendency was same as the results obtained in our previous studies [1,10]. From these results, it was revealed that the peak resolution and the stationary phase retention were affected by the rotation speed combination ratio more than by the revolution speed when using the conventional multilayer coiled column.…”

“…The CSC instrument used in the present studies was fabricated at the Machining Technology Center of Nihon University (Chiba, Japan). The design of the CSC instrument has been described in detail elsewhere [1], while the side motor was replaced with the more powerful one [10].…”

“…PTFE (polytetrafluoroethylene) tubing (Flon Kogyo, Tokyo, Japan) around the holder hub of 3 cm diameter forming four coiled layers between a pair of flanges spaced 5 cm apart. Each multilayer coil assembly consisted of alternating left-and right-handed coils conventionally used in the type-J CCC as described in detail elsewhere [10]. The total column capacity was 75.0 mL.…”

“…The organic-aqueous two-phase solvent systems used in the present studies were composed of ethyl acetate/1-butanol/water (1 : 4 : 5, v/v) for the upper mobile phase and (3 : 2 : 5, v/v) for the lower mobile phase [1,10,11]. The solvent mixture was thoroughly equilibrated in a separatory funnel at room temperature and the two phases were separated after two clear layers were formed.…”

“…In our previous studies, the CSC separation of 4-methylumbelliferyl (MU) sugar derivatives was examined using the conventional multilayer coiled column with both the lower and the upper mobile phases by varying the rotation speed of ω 2 [10]. With the lower mobile phase, almost constant peak resolution and stationary phase retention were obtained, but with the upper mobile phase different these values were obtained by changing the rotation speed of ω 2 .…”