離心分配層析單相溶劑系統中溶質延散之探討

Abstract

離心分配層析(centrifugal partition chromatography, CPC)和逆流層析(counter-current chromatography, CCC)都是使用液體為固定相及移動相的分離技術，但是二者流動的特性不相同。我們曾經在CCC螺旋管柱中使用單相系統，對溶質延散行為做過研究，本研究則是對CPC 在單相溶劑系統中，對於溶質延散行為之探討。 我們測試六種分子量大小迥異的溶質。在靜止的CPC 管柱中，其流析的訊號波形之理論板數值都相當高，而且理論板數是隨著溶質的擴散係數而增大。對個別溶質而言，理論板數會隨著流速增加而變大，亦即樣品的延散隨著流速增加而變小。和CCC 不同之處，是在流析過程中，並未有convection peak 和diffusion peak 的出現。在轉動之下，於低流速時，溶質的延散程度隨著轉速的提高而變小，理論板數也隨之上升。在高流速下，理論板數先隨著轉速增加而變小，當轉速繼續上升時，理論板數又隨之上升。探討流體之縱向(axial)和橫向(radial)延散之行為，我們認為在CPC 中之流體，並非像CCC 管柱中會形成穩定之層流(laminar flow)，而是兼具層流和紊流兩種性質。

Similar to counter-current chromatography (CCC), centrifugal partition chromatography (CPC) uses liquids as the stationary and mobile phases, although these two techniques have different hydrodynamic properties. We have investigated the solute dispersion behaviors of CCC in the previous study. In this work, we will examine the CPC solute dispersion in a single phase. We analyzed six solutes of considerable different molecular weights. Under static conditions, the eluted signals all demonstrated very high theoretical plate numbers (n). The n values increased with the increasing solute diffusion coefficient. In addition, their n values increased as the flow rate was elevated. In other words, the solute dispersion decreased with the increasing flow rate. Contrary to CCC, there appeared no signals with double peaks, i.e. convection and diffusion peaks. Under rotation, the solute dispersion decreased as the rotation speed increased at relatively lower flow rates. Thus, the theoretical plate number also increased. However, under higher flow rates, the n value decreased first with the rotation speed; then increased as the speed became higher. After considering the axial and radial dispersions of the fluid, we concluded that the flow in the CPC apparatus should include laminar and turbulent properties, unlike the stable laminar flow in the CCC.