Except for DNP-Hypro which was not examined, the DNP-derivatives of all protein-amino acids may be simply separated by three simultaneous chromatograms in different systems. One two-dimensional chromatogram and two one-dimensional chromatograms without protracted balancing, and operating simultaneously, can separate 14 of the 19 PTH-amino acids tested. Aided by a simple oxidation technique and by acid hydrolysis with subsequent thin layer chromatographic identification of the freed amino acid, which is stable with hydrolysis in any case, the missing five substances could be identified without further efforts.
Trans. of Experientia (Switzerland) v17 n4 p145-153, 15 Apr 1961.