[The separation of the 4-[4-(dimethylamino) phenylazo]phenylthiohydantoin derivatives of leucine and isoleucine on polyamid thin-layer sheets in the picomol range (author's transl)].

The separation of the 4-[4-(dimethylamino)-phenylazo]phenylthiohydantoin derivatives of leucine and isoleucine has so far not been possible. In this paper a method is described which separates these two amino acid derivates in the picomol range on polyamide thin-layer sheets. The system (10% formic acid/ethanol 10:9) can be used either in one or in two dimensions.