Extraction using organic solvents is a widely used technique for isolation of active ingredients obtained from bio-processes. The selection of optimal solvents and conditions is a systematic process for developing the procedure to isolate active substances. The objective of this work was the determination of the partitioning of lovastatin from a fermentation broth, present in two forms, lovastatin acid and lovastatin lactone, to solvents ethyl acetate, butyl acetate and isopropyl acetate. The effect of the contact time to reach equilibrium was studied and 1 h was chosen as an equilibration time. The influence of pH and temperature on partitioning was discussed and temperature of 23 degrees C and pH of 3 were determined as optimal extraction conditions for both ingredients. The solvent screening experiments were carried out at optimal conditions and equal affinity of ethyl acetate to both lovastatin forms was noticed. Isopropyl acetate and butyl acetate have shown higher selectivity toward lovastatin lactone than ethyl acetate. Different affinities of solvents to both solutes were discussed. Four-component equilibrium data (water/solvent/lovastatin acid/lovastatin lactone system) were measured and used to calculate binary interaction parameters of the UNIQUAC activity coefficients model that was further used to simulate an extraction process. (C) 2012 Elsevier B.V. All rights reserved.