Strategies of sunscreen separation by thin layer chromatography.

So far sunscreens separation has been achieved primarily by HPLC or TLC on RP-18 or (less frequently) unmodified silica gel as stationary phase. The conditions of chromatographic separation published so far are not suitable for many combinations of UV filters found commonly in cosmetic products. It is therefore reasonable to seek alternative conditions that would make it possible to separate these substances more effectively. Chromatographic separation of 15 UV filters used commonly for skin and hair protection was investigated. The effectiveness of separation of investigated compounds by normal- and reversed-phase thin layer chromatography was compared on RP-18, RP-2 and silica gel 60 stationary phases. In the case of some typical combinations of sunscreens normal-phase chromatography was found superior compared to the reversed-phase technique proposed in some published papers. It was suggested that sunscreens of totally different lipophilicity could be separated by multiple development TLC.