In this work, the partitioning of four N-(2,4-dinitrophenyl)-amino acids (DNP-amino acids) in novel Aqueous Two-Phase Systems (ATPS) based on 1-hexyl-3-methylimidazolium dicyanamide (C(6)Mim DCA) and biodegradable citrate organic salt, is evaluated. Firstly, the tie-lines and respective tie-line lengths for five ATPS (ionic liquid: CnMim DCA with n = 2,3,4 and 6 and C(4)pyr DCA (1) + sodium citrate tribasic dihydrate (2) + water (3)) were determined at T=298.15 K and atmospheric pressure. The tie-lines were correlated using Othmer-Tobias and Bancroft equations. The partition coefficients of N-(2,4-Dinitrophenyl)-glycine; N-(2,4-Dinitrophenyl)-L-alanine; N-(2,4-Dinitrophenyl)-L-valine and N-(2,4-Dinitrophenyl)-L-leucine in the ({C(6)Mim DCA (1) + sodium citrate tribasic dihydrate (2) + water (3)} ATPS were measured at T = 298.15 K and atmospheric pressure, aiming to evaluate the influence of the structure of the DNP-amino acids on the partition coefficients. (C) 2018 Elsevier B.V. All rights reserved.