Tube radial distribution phenomenon observed in an aqueous micellar solution of non-ionic surfactant fed into a microspace and an attempt of capillary chromatographic application

Abstract

A new type of tube radial distribution phenomenon was observed in an aqueous micellar solution of non-ionic surfactant that was fed into a microspace. A homogeneous aqueous solution containing 2 wt % Triton X-100 and 2.0 M sodium chloride was fed into a microchannel (40 μm in depth and 200 μm in width) in a microchip at a flow rate of 4.0 μL/min, where the microchip was maintained at a temperature of 34°C. The homogeneous aqueous solution changed to a heterogeneous solution with two phases in the microchannel; the surfactant-rich phase was generated around the middle of the channel, while the aqueous phase containing little surfactant was formed near the wall. The radial distribution of the surfactant was observed through Rhodamine B dissolved in the aqueous micellar solution with a bright-field microscope — CCD camera system. An open-tubular capillary chromatographic system was also tried to develop using the fusedsilica capillary tube (75 μm inner diameter and 120 cm length) as a separation column and the aqueous micellar solution as a carrier.