An improved method of separating amino acids as N-2,4-dinitrophenyl derivatives

Abstract

An improved method of separating ether-soluble DNP-amino acids by partition chromatography on short kieselguhr columns is described. DNP-amino acids are partitioned, largely as ions, between aqueous buffers and ethyl acetate; they form unusually narrow bands with a wide range of R values which are much less dependent on pH than in purely non-ionic partition. Columns of this type allow the isolation of almost any one of the common ether-soluble DNP-amino acids from a dinitro-phenylated mixture within an hour or two. The R values of many of the common DNP-amino acids on columns at different pH values are listed.