Liquid-liquid equilibrium of the acetonitrile-water system for protein purification

Abstract

Liquid-Liquid Equilibria (LLE) were measured at atmospheric pressure for the binary acetonitrile-water system at temperatures ranging from −1.3 to −18.6°C. Data points were taken using two methods, the cloud point method and the analysis of phase compositions using gas chromatography. Both methods show excellent agreement in their representation of the phase envelope. Temperature dependent NRTL (non-random two liquid) parameters were calculated from the binary data. The parameters calculated were τ₁₂ = 355.7−31.49_T(°C) and τ₂₁ = 967.2−26.59T(°C) with the a value held constant 0.3.