Phase equilibria and drug partitioning ability of betaine based aqueous two-phase systems

The aqueous two-phase system (ATPS) as an environmentally friendly technique has a high potential for extraction of drugs, proteins, metals, etc. In this work first the formation of ATPSs by betaine, which is a novel, low toxic, and high biodegradable material, and polyethylene glycol or phosphate salts (K₃PO₄ and K₂HPO₄) were investigated temperatures of 298.15, 308.15, 318.15 K and atmospheric pressure (≈ 85 kPa). The effect of increasing temperature on the binodal curves was investigated. The experimental binodal data were correlated using two empirical nonlinear three parameter expressions developed by Merchuk, and Zafarani-Moattar et al. and the two-parameter modified equation derived from effective excluded volume theory. Then, the experimental tie-line data were represented with Othmer-Tobias and Setschenow correlations. Finally, in these ATPSs the partition behavior of analgesic drugs, namely acetaminophen, salicylic acid, and ceftriaxone were investigated by measuring of partition coefficient and extraction efficiency. The trend of obtained results showed that the selected drugs were successfully extracted into the top phase of studied ATPSs with a partition coefficient greater than one and in the salt systems extraction efficiency was obtained up to 98% and in the case of polymer systems was obtained up to 8% at different tie-lines and it was found that the hydrophobicity of partitioned drugs is responsible for this phenomenon.