DURING recent work on the structure of bacitracin A, the identity of small amounts of aliphatic amines was confirmed by allowing them to react with 1 : 2 : 4-fluorodinitrobenzene1 and chromatographing the resulting dinitrophenyl derivatives on paper2. A number of primary aliphatic amines can readily be separated by chromatography on paper3, or by ionophoresis on paper at pH 7 using collidine acetate buffer2,4, and the spots revealed with ninhydrin. Schwyzer has separated certain primary, secondary and tertiary amines by paper chromatography, the spots being revealed by spraying with an indicator5. However, in view of the fact that the technique described here will give further evidence of the nature of a mixture of primary and secondary amines and ammonia, and that 0.5 µgm. or less of the dinitrophenyl-amines can be detected on the chromatograms under ultra-violet light, it seemed worth while to place it on record.