Abstract
Several water-soluble DNP-amino acids may be determined quantitatively by elution from IRC-50 columns with citrate/NaCl buffer. The following compounds have been separated: α-DNP-Lys, ε-DNP-Lys, DNP-Arg, di-DNP-His, DNP-Trp, and di-DNP-Lys, as well as free lysine, dinitrophenol, and dinitroaniline. Quantitation is by recording of the yellow color in the 360 mμ region; the ninhydrin color may also be recorded. The lower limits for analysis are approximately 0.01 to 0.05 μmole for the different compounds, using standard Technicon equipment.