Aqueous biphasic systems created with choline chloride-fructose natural deep eutectic solvents and polypropylene glycol 400 and usage of these systems for extraction of some commonly used drugs

Abstract

Natural deep eutectic solvents (NADESs) have gained a lot of attention in several fields and different applications, including separation of bio-molecules by aqueous biphasic system (ABS) containing these solvents. ABSs are well-known as green and non-toxic systems which are very important in pharmaceutical industry and drug extraction. In this work, a biodegradable ABS countering poly (propylene) glycol 400 and mixtures of choline chloride as hydrogen bond acceptor, HBA, and fructose, as hydrogen bond donor, HBD, with different molar ratios of choline chloride to fructose (i.e. 2:1 and 1:1) was made at T = 298.15 K and atmospheric pressure (≈85 kPa). The measured binodal data were fitted by two semi-empirical Merchuk and Zafarani-Moattar et al. equations. To see the effect of molar ratio of NADES on position of binodal, the experimental binodal data were also treated with binodal model. Compositions of five tie-lines for each molar ratio for this ABS were carefully determined to see whether the created ABS is a ternary system or the hydrogen bonding between NADES component is destroyed and a quaternary system is formed. The results suggest that, with dissolving these complexes in aqueous solutions the HBA: HBD stoichiometry used in NADES preparation are approximately preserved in the phases in equilibrium and the ABS act as a ternary-like system. The NRTL and UNIQUAC models were selected to correlate the tie-lines. Also, the performance of these ABSs to partitioning of some commonly used drugs, namely lamotrigine, salicylic acid and acetaminophen were investigated by calculation of partition coefficients, K, and extraction efficiencies, EE %, at different tie-lines. The trend showed that the hydrophobicity of mentioned drugs is responsible for partitioning of these drugs preferentially into the polymer-rich top phase. Finally, the equation proposed by Diamond-Hsu and its modified form were used to correlate the drugs experimental partition coefficients in the studied ABS system.