Conductimetric study of the interpolyelectrolyte reaction between chitosanand polygalacturonic acid

The interpolyelectrolyte reaction between chitosan hydrochloride (CHI) and sodium polygalacturonate (NaPGA) has been investigated by conductimetric me asurements. The composition of the reaction mixture, Z, was assessed by mon itoring the conductivity when a CHI solution was added to a solution of NaP GA, It was determined to be unity at the equivalence point, indicating a 1: 1 stoichiometry for the complex. The degree of complexation, theta, express ed as the fraction of groups reacted, was also obtained from the conductime tric measurements by means of a simple procedure. To this end the limiting ionic conductivities and transport coefficients of CHI and NaPGA were previ ously evaluated. It was found that theta varies with Z. It falls from unity to almost 0.8 as Z increases from 0.2 to 0.5 and then rises again up to 0. 85 for Z = 1. (C) 1999 Elsevier Science Ltd. All rights reserved.