title: Modified radioiodination and quality control methods for [125I]sodium iothalamate.
abstract: [125I]Sodium iothalamate can be prepared by the isotope-exchange method with the use of a contrast medium preparation (i.e. iothalamate sodium injection, USP, 80%). The initial isolation and purification of iothalamate from the contrast medium solution for radioiodination is tedious and time-consuming (i.e. 1 1/2 h for purification and overnight for drying). The new method uses iothalamic acid to replace iothalamate sodium injection as a starting material and reduces the heating time and multiple acid-washing steps during radioiodination to expedite the radiolabelling process. The radiochemical purity (RCP) of [125I]sodium iothalamate obtained from the new method was 98.9 +/- 1.3% (n = 30) versus RCP value of 99.2 +/- 1.0% (n = 25) from the old method with no significant differences between the two groups of RCP values. An RCP chromatographical system to separate and migrate the radiochemical species of [125I]sodium iothalamate from the origin is described in this paper.
authors.affiliation: Department of Diagnostic Radiology, Mayo Clinic, Rochester, MN 55905, USA.
authors.forename: J C
authors.initials: JC
authors.lastname: Hung
authors.forename: T J
authors.initials: TJ
authors.lastname: Herold
mesh_terms: D007457:Iodine Radioisotopes / Q000737:chemistry*; D007483:Iothalamic Acid / Q000737:chemistry*; D007553:Isotope Labeling / Q000379:methods*; D011786:Quality Control
chemical_list: D007457:Iodine Radioisotopes; D007483:Iothalamic Acid