Circulation chromatography

The main peculiarities and difficulties in the implementation of circulation chromatography are considered. The most impressive results obtained with the use of circulation liquid chromatography for the separation of isotopically substituted and isomeric organic compounds are given. The possibility of the preparative separation of the optical isomers of amino acid derivatives was demonstrated for the first time; thus, a new technique for the separation of optical isomers was developed. The capabilities of the circulation versions of gas-liquid and gas-adsorption chromatography are considered in detail. The possibility of the ultrafine separation of isotopically substituted compounds that differ by only one isotope atom, such as benzene and monodeuterobenzene, was demonstrated.