Abstract
The presented methods are the combination of Amberlite IRC-50 and Duolite C-25 column chromatographies by using several eluants, consisting of dilute HCl containing various amounts of acetic acid, acetone or methylethylketone. Recovery of 22 DNP-amino acids tested is 80-100%, except a low value (60-80%) for (DNP)2-ornithine. The presented methods can separate DNP-allothreonine and DNP-alloisoleucine from the respective isomers. About 0.5 mg each of DNP-amino acid can be applied per square centimeter.