Electrochemical Study of Theophylline - Urea Interaction Using Square Wave Voltammetry

Abstract

In this work, the interaction between theophylline (TP) which gives a stable well-defined reduction peak at (1.07) V versus Ag/AgCl. Sat. KCl/ in phosphate buffer solution (pH=7) and urea was studied using square wave voltammetry (SWV) technique. Also, the binding constant and the thermodynamics parameters have been calculated. Different temperatures (288, 293, 298, 298, 303, 308 and 310) ºK were used to study the effect of temperature on binding constant (K). The results showed that the binding constant (K) decreased with increasing temperature. This is as a result of the negative value of enthalpy (-31.07)KJ.mol-1. The negative value of Gibbs energy (-13.632 x 102_ -12.296 x 102) KJ.mol-1 indicates that the interaction is spontaneous and could be due to van der Waals forces or hydrogen bonds effect (weak interaction).