Abstract A centrifugal counter-current chromatographic method for preparative purification of commercial tetrabromotetrachlorofluorescein and Phloxine B (D&C Red Nos. 27 and 28, respectively) was developed. Ethyl acetate— n-butanol–0.01 M ammonium acetate (1:1:2) was used as the two-phase solvent systems. Each purification trial involved 50 mg of sample and yielded 22 mg (±2 mg) of pure dye. The purity of the product was measured by hihg-performance liquid and thin-layer chromatography and was found to be 99.9%. The partition coefficients of these compounds were found to be highly concentration-dependent in the two-phase solvent system used. If this problem can be circumvented, then the counter-current chromatographic method can be extended for use with gram quantities of dye.