Aqueous two-phase system (polyethylene glycol + ionic liquid) for extraction of α-amylase: phase diagrams, systems characterization and partition study

The increasing demand for safe and effective methods for the separation of biological materials combining the advantageous properties of polyethylene glycol (PEG) (1500 g mol−1 or 4000 g mol−1) and ionic liquid has led to attractive and promising applications of the new aqueous biphasic systems. In this work, the liquid–liquid extraction process with aqueous two-phase systems (ATPS) was studied for α-amylase partitioning. The phase diagrams composed of PEG (1500 or 4000) g mol−1 + 1-ethyl-3-methylimidazolium chloride + water, were determined experimentally by the turbidimetric method at different temperatures T = (293.15, 303.15, 313.15 and 323.15) K. The effect of temperature and polymer molar mass on the phase diagrams, as well as the phase densities, refractive indexes and electrical conductivity were evaluated. Subsequently, the α-amylase partitioning was performed, where the partition coefficient was determined, besides the activity and selectivity. It was found that a temperature decrease and a polymer molar mass increase favored the formation of two phases. It was also found that α-amylase showed a preference for the bottom phase composed of PEG and the systems composed of PEG 1500 presented better results.