268 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Figure 2. Apparatus for continuous elution TLC

THIN-LAYER CHROMATOGRAPHY 269 TOTAL DYE MULTIPLE DEVELOPMENT (2 mm. Plate) BAND RESOLUTION BAND EXTRACTION CENTRIFUGATION and FILTRATION EVAPORATION PURIFICATION (0.25mm. Plate) Figure 3. Isolation procedure CONCLUSION TLC of oxidative dyes is a less than perfect answer for the dye chemist because of prob- lems associated with the chemical composition of the dyes. However, to date, TLC has been the single most effective method for providing pure components for structural determinations. It is the only standard analytical technique able to identify the com- position of the already-formed dyes, simply because it indicates colors and the range of mobilides of the different product components whch can form from specific precursors. The chromatographic separation of the oxidative products will make it possible to deduce trends in the pattern of dye developments. ACKNOWLEDGMENT This work was carried out at Gillette Research Institute. I wish to acknowledge my gratitude to the late Dr. William Tolgyesi for his many helpful suggestions. REFERENCES (1) R. B. Symth and G. G. Mckeown, The analysis of arylamines and phenols in oxidation-type hair dyes by paper chromatography, J. Chromatogr., 16, 454 (1964).