Modelling the separation of amines by high performance liquid chromatography I. Linear diamines NH2(CH2)nNH2 (n = 2-10)

This paper describes the results of a study on the HPLC retention behaviour of general formula NH2(CH2)nNH2 (n=2-10), linear diamines using strong cation exchange resin and amperometric detector. A number of eluents were used for this purpose: citric acid-Na2SO4, H2SO4-Na2SO4, HCl-NaCl, HClO4-NaClO4 and HClO4-NaClO4-CH3CN. The last eluent ensures smaller retention times (tR). The influence of the anion on tR values has been discussed. Empirical relationships between tR and capacity factors K´ with Na+ concentrations and with aliphatic chain length, in different experimental conditions, are reported. The influence of amine protonation constants on logK´ values is also discussed. Some examples of separation are reported.