Spiral Countercurrent Chromatography

Abstract

For many years, high-speed countercurrent chromatography conducted in open tubing coils has been widely used for the separation of natural and synthetic compounds. In this method, the retention of the stationary phase is solely provided by the Archimedean screw effect by rotating the coiled column in the centrifugal force field. However, the system fails to retain enough of the stationary phase for polar solvent systems such as the aqueous-aqueous polymer phase systems. To address this problem, the geometry of the coiled channel was modified to a spiral configuration so that the system could utilize the radially acting centrifugal force. This successfully improved the retention of the stationary phase. Two different types of spiral columns were fabricated: the spiral disk assembly, made by stacking multiple plastic disks with single or four interwoven spiral channels connected in series, and the spiral tube assembly, made by inserting the tetrafluoroethylene tubing into a spiral frame (spiral tube support). The capabilities of these column assemblies were successfully demonstrated by separations of peptides and proteins with polar two-phase solvent systems whose stationary phases had not been well retained in the earlier multilayer coil separation column for high-speed countercurrent chromatography.

Preparative separation and identification of novel subsidiary colors of the color additive D&C Red No. 33 (Acid Red 33) using spiral high-speed counter-current chromatography

“…(Zeus Industrial Products, Orangeburg, SC, USA) inserted into the spiral grooves. Photographs of the instrument and a similar STS rotor have been previously published [9,24]. …”

“…2) from the main component 1 and from each other using spiral high-speed counter-current chromatography (HSCCC) [9]. The chemical identification and characterization of the separated components are also presented.…”

“…That alternative consists of a spiral-tube assembly column in which the inert plastic tube is coiled into a rigid spiral frame [9]. This HSCCC variant, called spiral HSCCC, has been applied to the separation of peptides and proteins [9,38,39] and to the separation of gram quantities of a highly polar polysulfonated color additive without using a hydrophobic counterion in the stationary phase [40]. …”

Tubing modifications for countercurrent chromatography (CCC): Stationary phase retention and separation efficiency

“…Yet, its relatively high viscosity η M , low interfacial tension σ and small density difference Δρ between the upper and lower phase (Table 1) were rather unfavorable for CCC [23]. In addition, the long settling time (t s =29 s) indicated that both phases did not distribute fast to the respective head and tail end [42,43].…”

“…It was suspected that the fluid dynamics occurring inside the tubing were influenced in such a manner that undesirable longitudinal flow of the mobile phase could be interrupted [20]. More recently, a similar approach was followed for the improvement of the spiral tube support assembly for CCC (specially developed for the separation of extremely polar compounds with polar solvent systems) by changing the shape of the tubing through compressions perpendicularly along the length of the tubing [21][22][23]. Convoluted tubing was introduced to improve the retention of the stationary phase during the scale-up of slow-rotary CCC by Du and Winterhalter and it has been successfully applied in the purification of natural products [24][25][26][27].…”