Amino Acid and Block Copolymer-Based ABS: An Efficient Extraction Tool for PPIs and Consequent Recovery of the Polymer

Aiming to construct a biocompatible aqueous biphasic system (ABS), amino acids and a block copolymer, poly(propylene glycol)-block-poly(ethylene glycol)-block-poly-(propylene glycol) (PPG-PEG-PPG), have been employed. Glycine and L-proline can successfully salt out PPG-PEG-PPG and can form a biphase even at room temperature, whereas L -alanine requires the temperature to be increased to at least 318 K at normal atmospheric pressure to form an ABS with the block copolymer. The phase diagrams for all the systems have been constructed using a turbidometric method at different temper-atures, and the corresponding binodal graphs are plotted with the help of the Merchuk equation. An increase in temperature leads to an increase in the biphasic region. The tie line lengths, slope of the tie lines, and compositions of both the phases of the corresponding ABSs have been determined using the lever arm rule. The presence of amino acids in the place of ionic salts as one of the phase-forming components makes the ABSs eligible to extract medically relevant molecules. Herein, proton pump inhibitors (PPIs), one of the most prescribed medicines in the world, are extracted using the newly designed amino acid and block copolymer-based ABSs. The complete extractions of rabeprazole and pantoprazole are achieved using the glycine-based ABS, whereas similar to 83% of esomeprazole is extracted with the same ABS. The extraction efficacies of the other two amino acid-based ABSs are also noticeable. After the extraction, the block copolymer-rich phase is regenerated using thermoseparation and adsorption techniques, which makes the ABS a much greener and cost-effective methodology in extraction chemistry.

Automated summary

This study aims to construct a biocompatible aqueous biphasic system (ABS) using amino acids and a block copolymer. The phase behavior of the systems was determined, and the newly designed ABSs were successfully used to extract medically relevant molecules from proton pump inhibitors. The block copolymer-rich phase was regenerated using thermoseparation and adsorption techniques, making this ABS method more environmentally friendly and cost-effective.