A new procedure for fractionation of mixtures by solvent distribution.

The value of systematic distribution between immiscible solvents for the resolution of mixtures has long been recognized, but it was not until the work of Craig (1) that its full potentialities were appreciated. With the development of an apparatus for carrying out a large number of simultaneous distributions between immiscible solvents, Craig and Post (2) introduced a new and very effective analytical tool to organic chemists and biochemists. The application of their so called counter-current techniques to chemical problems has led to a closer realization of the goal of absolute chemical purity and has accounted for the separation and identification of the components of many mixtures, The use of the Craig apparatus, however, has been somewhat limited because the cost has been prohibitive to many laboratories. In the course of investigations on natural plant growth regulators in this laboratory, a simple automatic solvent distribution apparatus operating on a principle different from that of the Craig apparatus has been devised for use in large scale fractionation procedures. Because the apparatus is inexpensive and requires little attention during the distribution, it should prove to be very useful in the isolation and purification of biological materials. The design is novel in that equilibration of the solute between immiscible solvents is achieved without any mechanical agitation.