Preparation of no-carrier-added 4-[131i]iodoantipyrine using chloramine-T

The blood flow reagent 4‐iodoantipyrine, labelled with 131I or 125I, was prepared by allowing aqueous antipyrine to react with either no‐carrier‐added 131I−I or 125I−I in the presence of chloramine‐T. Purification of 4‐[131I]iodoantipyrine was performed by reversed‐phase liquid chromatography and resulted in a 99 ± 1% radiochemically pure product in an overall 90% yield. The use of iodogen for oxidation of the radioiodine was also investigated.