Michrochip chromatography using an open-tubular microchannel and a ternary water-ACN-ethyl acetate mixture carrier solution.

A capillary chromatography system has been developed using a ternary mixed-solvents solution, i.e. water-hydrophilic/hydrophobic organic solvent mixture as a carrier solution. Here, we tried to carry out the chromatographic system on a microchip incorporating the open-tubular microchannels. A model analyte solution of isoluminol isothiocyanate (ILITC) and ILITC-labeled biomolecule was injected to the double T-junction part on the microchip. The analyte solution was delivered in the separation microchannel (40 μm deep, 100 μm wide, and 22 cm long) with the ternary water-ACN-ethyl acetate mixture carrier solution (3:8:4 volume ratio, the organic solvent rich or 15:3:2 volume ratio, the water-rich). The analyte, free-ILITC and labeled BSA mixture, was separated through the microchannel, where the carrier solvents were radially distributed in the separation channel generating inner and outer phases. The outer phase acts as a pseudo-stationary phase under laminar flow conditions in the system. The ILITC and the labeled BSA were eluted and detected with chemiluminescence reaction.