Liquid chromatography on a centrifugal platform for separation and collection of water-soluble dyes

A reversed-phase chromatographic process is developed on a centrifugal platform to separate and collect water-soluble dyes from a mixture. A separation column filled with C18-reversed phase silica gel was used to separate the components from a mixture and the eluate was collected by a series of collecting chambers. The purified components can then be identified and extracted from the collecting chambers. The effects of the silica gel's particle size (7-10, 20-45, and 46-63 µm) and the platform's rotational speed (1000, 1500, 2000 RPM) on the separation and collection efficiency were investigated. Experimental results showed that dye separation could be well performed in the column with smaller-sized silica gels (7-10 µm) under a low rotational speed (1000 RPM). However, for the eluate collection, the high eluent flowrate and long processing time resulted in a convective band-broadening problem in the collecting chambers, which affected the recovery ratio of the dyes. Experimental results showed that the convective band broadening effect can be reduced by reducing the flowrate, shortening the collecting time, and switching the eluent to a different composition. The best recovery ratio of the dyes in the current design can be achieved by using the column with a powder size distribution of 46-63 µm and operating at the rotational speed of 1500 RPM. This platform can process a sample volume of 1 μL and the processing time is about 30 min. Since the only instrument used is a motor, the complete chromatographic process, from separation to fraction collection, can be carried out on a centrifugal platform at a low cost.