pH-Zone-refining CCC was successfully applied to the purification of various kinds of hydroxyxanthene dyes including Red No. 28, Red No. 27, Red No. 22, Red No. 3, Orange No. 5, Orange No. 10, Eosin YS, tetrachlorofluorescein, etc. Using the same solvent system, the major components of these dyes were fractionated in a concentrated state in 3- 12 hours. The sample size varied from 350mg to 6g and both purity and yield increased with the increased sample size as demonstrated in the separation of Orange No. 5.
