Countercurrent chromatographic separation of biotic dicarboxylic acids with polar two-phase solvent systems using cross-axis coil planet centrifuge

Various aliphatic dicarboxylic acids were separated by counters current chromatography using cross-axis coil planet centrifuge (cross-axis CPC) equipped with a pair of eccentric coil assemblies mounted in an off-center position. Partition coefficients of these samples were optimized by adjusting the volume ratio of a polar two-phase solvent system composed of methyl t-butyl ether/1- butanol/acetonitrile/aqueous 0.1% trifluoroacetic acid., Maleic acid and fumaric acid were separated at a volume ratio, of 5:0:0:5 by the lower aqueous phase mobile, while tartaric acid, succinic acid, and fumaric acid were well resolved by a more polar solvent system at a volume ratio of 2.9:0:2.9:4.3. Using the most polar binary solvent system composed of 1-butanol/water, oxalic acid, malonic acid, and succinic acid were resolved from each other by the lower aqueous phase mobile. The overall results of the present studies indicate that the cross-axis CPC is useful for the separation of various polar organic acids.