Microinjection-microspectroscopy of single oil droplets in water: an application to liquid/liquid extraction under solution-flow conditions

A microinjection-microspectroscopy system combined with a fluid manifold was developed to manipulate and analyze 'single' micro-oil-droplets in water. Water was poured into a flow cell set on a microscope stage through a microcapillary tube. A single tributyl phosphate (TBP) microdroplet was then pushed out to the water phase in the cell through an another tiny capillary tube and held on the top end of the tube. These procedures made it possible to inject a single microdroplet exclusively into the cell. The technique was applied to study a time course of liquid/liquid extraction processes of an AI-DHAB chelate (DHAB=2,2'-dihydroxyazobenzene) from water to single TBP microdroplets. The extraction rate of Al-DHAB was determined for individual microdroplets and the results were discussed in terms of the solution flow rate and the droplet diameter. (C) 2000 Elsevier Science B.V. All rights reserved.