The Micro-Flow Reaction System Featured the Liquid–Liquid Interface Created with Ternary Mixed Carrier Solvents in a Capillary Tube

Abstract

A micro-flow reaction system was developed in which liquid–liquid interface was created based on the tube radial distribution of ternary mixed carrier solvents. The system was constructed from double capillary tubes having different inner diameters (100 and 250 μm i.d.). The smaller tube was inserted into the larger one through a T-type joint. The reaction of a protein with a fluorescence derivatizing reagent was adopted as a model. A water–acetonitrile mixture (3:1 volume ratio) including bovine serum albumin (hydrophilic) was delivered into the large tube from the inside through the small tube and an acetonitrile–ethyl acetate mixture (7:4 volume ratio) containing fluorescamine (hydrophobic) as a derivatizing reagent was delivered from the outside through the joint. Solutions were mixed through the double capillary tubes to promote ternary mixed carrier solvents (water–acetonitrile–ethyl acetate; 1:2:1 volume ratio). The liquid–liquid interface was created based on the tube radial distribution of ternary solvents in the larger tube. The derivatization reaction was performed in the larger, or reaction, tube in the micro-flow system. The fluorescence intensity of the fluorescamine-derivatized bovine serum albumin obtained by the system, which specifically included the kinetic liquid–liquid interface in the tube, was greater than that obtained through a batch reaction using a homogeneous solution of water–acetonitrile (1:2 volume ratio).