Synchronous Flow-through Coil Planet Centrifuge Research Articles

Studies on a new cross-axis coil planet centrifuge for performing counter-current chromatography: I. Design of the apparatus, retention of the stationary phase, and efficiency in the separation of proteins with polymer phase systems

An improved model of the cross-axis synchronous flow-through coil planet centrifuge has been designed in light of previous studies. The apparatus has a versatile feature in that both analytical and preparative columns can be accommodated in both off-center and central positions. Each has merit in separations. Retention of stationary phase was examined with various two-phase solvent systems used for the separation of biopolymers. Both analytical and preparative columns showed satisfactory retention of the stationary phase under optimum conditions. The apparatus was evaluated in separation of a set of protein samples using a polyethylene glycol—potassium phosphate biphasic system. In both types of columns all proteins were resolved with partition efficiencies of 260 to 670 theoretical plates. Further studies indicated that the relatively low partition efficiency of proteins is mainly attributed to their high molecular mass or molecular heterogeneity within each species rather than due to the high viscosity of the polymer phase system.

Cross-Axis Synchronous Flow-Through Coil Planet Centrifuge (Type XLL) III. Performance of Multilayer Coils in Preparative Separation of Dipeptides

Abstract Performance of the type-XLL cross-axis coil planet centrifuge with three different size of the multilayer coils was evaluated by separating dipeptide samples on a polar biphasic solvent composed of n-butanol/acetic acid/water (4:1:5, v/v/v). Best results were obtained from the large helical diameter coils with β values of 1.00-1.20 [1]| by eluting with the upper nonaqueous phase at 120 ml/h. The four dipeptides. L.-tryptophyl-L-tyrosine, L-leucyl-L-tyrosine, L-valyl-L-tyrosine and L-tyrosylglycine were completely rcsolved in 9 hours with high peak resolution (Rs > 1.5).

Cross-axis synchronous flow-through coil planet centrifuge (type XLL) : II. Speculation on the hydrodynamic mechanism in stationary phase retention

The hydrodynamic mechanism involved in the retention of stationary phase in the present x-axis coil planet centrifuge system is discussed. A statistical treatment of the retention data disclosed important clues such as the effect of the inward-outward elution mode, the close correlation between the planetary motion and the head—tail elution mode, and the superior retention capacity of the left-handed coils. The combined effects of the radial and lateral centrifugal force field derived from the mathematical analysis of acceleration acting on the coil provide an explanation for the phenomena.

Cross-axis synchronous flow-through coil planet centrifuge (type XLL) : I. Design of the apparatus and studies on retention of stationary phase

the fourth prototype holds a pair of column holders in the lateral position at 15 cm from the center of the rotary shaft horizontally mounted on the rotary frame at 7.6 cm from the central axis of the apparatus. Using short coils of 2.6 mm I. D. PTFE (polytetrafluoroethylene) tubing with 7.6 cm and 24 cm helical diameters, retention of the stationary phase was measured in ten pairs of two-phase solvent systems under various experimental conditions. Satisfactory retention was obtained by choosing proper combinations of three factors, i. e., the direction of planetary motion, head—tail elution mode, and inward—outward elution mode. The polar butanol solvent systems showed excellent retention from 65 to 80% in the 7.6 cm helical diameter left-handed coil

Improved cross-axis synchronous flow-through coil planet centrifuge for performing counter-current chromatography : I. Design of the apparatus and analysis of accelaration

A novel design of the cross-axis synchronous flow-through coil planet centrifuge is introduced. The apparatus holds a pair of large coil holders symmetrically, one on each side of the rotary frame, at a lateral position 12.5 cm from the center of the holder shaft held 10 cm from the centrifuge axis. Mathematical analysis of acceleration generated by the planetary motion of the apparatus revealed a unique centrfugal force field which promises high retention of the stationary phase in the multilayer coil to perform efficient preparative-scale counter-current chromatography.

Improved cross-axis synchronous flow-through coil planet centrifuge for performing counter-current chromatography : II. Studies on retention of stationary phase in short coils and preparative separations in multilayer coils

Performance of the apparatus was evaluated in terms of stationary phase retention, partition efficiency and sample loading capacity. Preliminary studies with short coils revealed high retention of the stationary phase under a proper combination of the head—tail elution and planetary motion. Preparative capability of the apparatus was successfully demonstrated on efficient multigram separations of 2,4-dinitrophenyl amino acids, indole auxins, and bacitracin in a pair of large multilayer coils with a total capacity of 1.5 1.

Cross-axis synchronous flow-through coil planet centrifuge for large-scale preparative counter-current chromatography : III. Performance of large-bore coils in slow planetary motion

A preparative capability of the present cross-axis synchronous flow-through coil planet centrifuge was demonstrated with 0.5 cm I.D. multilayer coils. Results of the model studies with short coils indicated that the optimal separations are obtained at low revolutional speeds of 100–200 rpm in both central and lateral coil positions. Preparative separations were successfully performed on 2.5–10 g quantities of test samples in a pair of multilayer coils connected in series with a total capacity of 2.5 l. The sample loading capacity will be scaled up in several folds by increasing the column width.

Cross-axis synchronous flow-through coil planet centrifuge for large-scale preparative counter-current chromatography : II. Studies on partition efficiency in short coils and preparative separations with multilayer coils

A series of experiments was conducted to evaluate the partition efficiency of the cross-axis synchronous flow-through coil planet centrifuge. The preliminary studies indicated that short coils (5 m) mounted on 15- and 25-cm diameter holders in either a central or a lateral location produce a high partition efficiency of over 100 theoretical plates. Under the optimum operating conditions, the preparative capability of the countercurrent chromatograph was demonstrated on gram-scale separations of DNP-amino acids and dipeptides in a pair of multilayer coils connected in series with a total capacity of 1600 ml.

Preliminary applications of cross-axis synchronous flow-through coil planet centrifuge for large-scale preparative counter-current chromatography

The cross-axis synchronous flow-through coil planet centrifuge with a 20-cm revolutional radius and a total capacity of 1600 ml was successfully applied to preparative counter-current chromatography of various biological samples, which include sea buckthorn extract, steroid reaction mixture, indole plant hormones, and dinitrophenylamino acids. The present system offers advantages of stable balance of the centrifuge, a large column capacity, and high resolution.

Cross-axis synchronous flow-through coil planet centrifuge for large-scale preparative counter-current chromatography : I. Apparatus and studies on stationary phase retention in short coils

Using a new cross-axis synchronous flow-through coil planet centrifuge with a 20-cm revolutional radius, the retention of the stationary phase for nine solvent systems was studied with short coils mounted at two different locations on three holders with 5-, 15- and 25-cm hub diameters. Coils mounted 10 cm to the left of the center of a holder produced a much improved retention of most of the solvent systems compared with the same coils mounted at the center of the holder. In the lateral coil position the retention was found to be affected by the direction of the planetary motion and the head-tail elution mode. This phenomenon may be attributed to the effect of the lateral force field acting asymmetrically between the upper and lower halves of the coil.

Cross-Axis Synchronous Flow-Through Coil Planet Centrifuge Free of Rotary Seals for Preparative Countercurrent Chromatography. Part II. Studies on Phase Distribution and Partition Efficiency in Coaxial Coils

Abstract Potential capability of the apparatus in performing countercurrent chroma-tography has been examined with three different types of coiled columns, all coaxially mounted around the holder. In single-layer coils, typical solvent systems display characteristic hydrodynamic distribution which ensures a stable retention of the stationary phase against heavy sample loading in preparative separations. Direct observation of the hydrodynamic motion in the rotating spiral column revealed vigorous mixing of the two solvent phases throughout the area which promises a high partition efficiency of the present method. Gram-quantity preparative separations were performed in the multilayer coil with two different sets of test samples: Isocratic elution of dinitrophenyl amino acids yielded high partition efficiency of 1600 theoretical plates while the versatility of the method was demonstrated on gradient elution of dipeptides including two pairs of sequential isomers.

Cross-Axis Synchronous Flow-Through Coil Planet Centrifuge Free of Rotary Seals for Preparative Countercurrent Chromatography. Part I. Apparatus and Analysis of Acceleration

Abstract A novel type of the coil planet centrifuge is introduced. The apparatus holds a coil holder in such a way that the axis of the holder is positioned perpendicular to and at a fixed distance away from the centrifuge axis. In maintaining the above orientation the holder undergoes synchronous planetary motion, i.e., revolution around the central axis-of the centrifuge and rotation about its own axis at the same angular velocity. Mathematical analysis of acceleration generated by this planetary motion revealed a unique distribution pattern of centrifugal force vectors which promises a high performance of the present scheme in counter-current chromatography.

Foam counter-current chromatography with the cross-axis synchronous flow-through coil planet centrifuge

A novel coil planet centrifuge system performs efficient foam separation in a long multilayer coil. Potential capability of the method was successfully demonstrated in separations of two sets of test samples using sodium dodecyl sulfate as a foaming agent. Rhodamine B with high foam affinity was quickly separated from Evans blue lacking foam affinity. A high concentration of salts such as disodium hydrogenphosphate in the surfactant solution effectively lowered the foam affinity of basic dyes, yielding complete peak resolution of rhodamine B and methylene blue according to a subtle difference in foam affinity.