Analytical Sciences

Chemical and Thermodynamic Characteristics of the Isotopic Exchange Reaction between Radioiodine and Iodohippuric Acid Isomers

M. S. EL-SHAHAWI,**  G. EL-SHABOURY,* M. A. M. ALY,* and M. EL-TAWOOSY*

*Radioisotope Production Division, Hot Labs. Center, Atomic Energy Authority, Code No. 13759, Cairo, Egypt
**Chemistry Department, Faculty of Science at Damietta, Mansoura University, Damietta, Egypt

The parameters affecting the absolute radiochemical yield of the isotopic exchange reaction between radioiodine (¹²⁵I_-) and iodohippuric acid isomers on molten ammonium acetate as a medium exchange at 120°C without any carrier added (radioiodine, ¹²⁵I_-) was determined. The isotopic exchange reactions of radioiodine as ¹²⁵I^- for iodine-127 of o- and p-iodohippuric acid isomers occur more rapidly than m-iodohippuric acid isomer. These reactions proceed by nucleophilic second order substitution reaction. The kinetics and thermodynamic parameters of these isotopic exchange reactions were determined. The absolute radiochemical yield and radio pharmaceutical purity were determined by HPLC and TLC techniques.

J-STAGE: View this article in J-STAGE