Partitioning Behavior of Glatiramer Acetate and Its Constituent Amino Acids in Aqueous Two‐Phase System Containing Sorbitol/Fructose and Acetonitrile

ABSTRACT A carbohydrate‐based aqueous two‐phase system (ATPS) containing sorbitol/fructose and acetonitrile was utilized to separate constituent amino acids of glatiramer acetate (GA), including alanine, glutamic acid, lysine, and tyrosine. Purification of GA from its amino acid contaminants can be seen as a pretreatment step prior to chromatography‐based techniques. The study evaluated how the type and concentration of carbohydrates affect the partitioning of amino acids and glatiramer acetate. In all cases, these compounds were found to partition to the carbohydrate‐rich phase. The influence of pH on partitioning was examined, showing that a sorbitol‐based system at pH 6 resulted in better GA partitioning among other pHs and fructose‐based systems. Additionally, quantitative structure–activity relationship analysis was used to predict the partitioning behavior of components in ATPSs, with results indicating that components in sorbitol‐based systems can be accurately predicted. For each ATPS, the optimum feed composition, based on selectivity, was found to be (fructose 15 wt% + acetonitrile 40 wt%) and (sorbitol 17 wt% + acetonitrile 35 wt%), respectively. The optimal partition coefficients for GA were determined as 0.213 for the system of (fructose 15 wt% + acetonitrile 40 wt%) and 0.119 for the mixture of (sorbitol 19 wt% + acetonitrile 35 wt%). The partitioning behavior of GA demonstrated distinct characteristics compared to some of its constituent amino acids, indicating promising potential for the application of ATPS in separation processes.