Fundamental Research On Multilayer Coil Planet Centrifugal Process And Its Application

Multilayer coil planet centrifuge, also called high-speed countercurrent chromatography (HSCCC), is a new type of liquid-liquid partition chromatography. HSCCC provides an advantage over the conventional column chromatography by eliminating the use of a solid support where dangers of irreversible adsorption from the support, loss and contamination of the sample are inevitably present. So far, it has been widely applied to analytical and preparative scale separations of natural product and other chemical substances. HSCCC utilizes a special synchronous planet motion which produces a unique unilateral hydrodynamic motion of the two solvent phases, and the special motion can guarantee the retention of the stationary phase and efficient mixing and settling of the two-phase solvent system against the flow of the mobile phase to produce excellent peak resolution, and provides the efficient partition and separation of the sample.Chapter 1 of the dissertation gives the literature review about the high-speed countercurrent chromatography, including development of CC-C, unilateral hydrodynamic equilibrium mechanism of HSCCC, application of HSCCC, selection of the two-phase solvent system, elution mode, retention of the stationary phase, development of HSCCC apparatus and its scale-up.Chapter 2 deals with the retention of the stationary phase. A mathematical model was proposed to describe the influences of operation conditions (flow rate, rotation speed), physical properties (density difference, viscosity and interfacial tension) and instrument parameters (tube diameter, revolution radius) on the retention of the stationary phase, by building on the flow behavior of the two phases in the coiled column, laminar flow or droplet flow. The model parameters, together with the critical value at which the transition between the laminar flow and droplet flow occurs, were determined by the analysis of experimental data of the retention of the stationary phase measured in this work. Furthermore, the proposed model wastested to predict the literature data of retention of the stationary phase for seven HSCCC apparatuses including preparative, semi-preparative and analytical types, with the coiled column material of polytetrafluorethylene (PTFE) and stainless steel, and for 16 two-phase systems.Chapter 3 explores the relationships between the operational variables affecting HSCCC, such as the influence of flow rate, rotation speed on the peaks retention time, peaks width, the relationship between the peaks width and peaks retention time. According to these relationships, resolution and efficiency can be estimated.Chapter 4 deals with the sample capacity of preparative HSCCC. Based on the plate theory of Van Deemter, the effects of the sample load including the sample volume, concentrantion and sample mass on the peak retention time and peak width were investigated in a preparative HSCCC, and the theory of Van Deemter was verified in preparative high-speed countercurrent chromatography. Furthermore, the factors limiting the mass load including the resolution between the peaks, the partition isotherm and the sample solubility were also discussed.Chapter 5 deals with the mass transfer and the elution profile model of HSCCC. A transfer-dispersive model was proposed to describe the effluent concentration profile, based on the assumption that retention of a peak is caused by partitioning over two phases, and peak broadening is caused by axial dispersion and mass transfer limitation. The model parameters of axial dispersion coefficient and volumetric mass-transfer coefficient were obtained by comparing model simulations to experimental data. Two correlations about axial dispersion and mass transfer coefficient were obtained. The model presented in this chapter can predict the effluent concentration profiles accurately with the known partition coefficient and the retention of the stationary phase.Chapter 6 deals with the application of preparative HSCCC in separation and purification of two main bioactive components, namely, atractylon and atractylenolide III from the traditional Chinese medicine Atractylodes macrocephala. First, the extraction process of essential oil of Atractylodes macrocephala wasoptimized, and then the HSCCC separation conditions including two-phase solvent system, flow rate, rotation speed, temperature, sample load and elution mode were also optimized. Under the optimized condition, one-step preparative separation of atractylon and atractylenolide III from essential oil of Atractylodes macrocephala was achieved.In Chapter 7, the final section, the research contents of this dissertation were summarized, and several aspects concerning the further investigations of HSCCC are suggested.