(2019-03-04) On the comparison between diafiltration and isothermal titration calorimetry. Determination of the amount of analytes bound to water-soluble polymers
Description
Aqueous systems composed of low molecular-weight species (LMWS) and water-soluble polymers (WSP) present important technological applications. Therefore, continuous advances on characterization techniques are crucial to gain a better understanding on how these systems interact and subsequently further modulate their properties by tuning their preparation process. For that matter, this work aims at comparing a developing characterization tool, diafiltration (DF), with a well-established method for studying LMWS / macromolecule interactions, isothermal titration calorimetry (ITC). Chlorpheniramine maleate (CPM) and poly(sodium 4-styrenesulfonate) (PSS) are used as a model aqueous LMWS / WSP system. The comparison is based on the CPM fraction bound to PSS measured by both methods. The values obtained are (0.89 ± 0.00) and (0.88 ± 0.05) for DF and ITC, respectively. The similarity between these values is noteworthy considering the dissimilarity of the process on which both techniques are based (filtration and heat exchange). This work constitutes a first step on setting DF and ITC as complementary and supporting techniques. Additional implications from these results are further discusse