Gel filtration in aqueous systems as developed by FLODLN AND PORATH in the years Ig$3--1960 has many valuable features, the most important of which are :
(I) Fractionation according to molecular size.
(2) Easy handling of the material.
(3) Good stability of the chromatographic bed. (4) Possibility of chromatography of labile substances without denaturation.
(5) Permissibility of high sample concentrations because of the linearity of partition isotherms.
There is therefore considerable interest in extending the technique to include organic solvents.
It was very soon found that Sephadex@ of the G-series, the classical material for gel filtration in aqueous solutions, could be used in some polar organic solvents, Suitable solvents include glycol, formamide and dimethylsulphoxide, although these have not been frequently used. The use of mixtures of water and the lower alcohols, notably ethanol has, however, often been reported in the literature, In rg6o, VAUGHAN reported the use of cross-linked polystyrene as a chromatographic medium with aromatic hydrocarbons as solvents'. This material could be used for the determination of molecular weight, for distribution analysis etc. CORTB-JONES also used the same materia12, while BREWER used vulcanized rubber latexa. Since then, polystyrene gels have been developed by MOORE for use mainly with non-