Kit type labelling of [123I] metaiodobenzylguanidine

We have examined the labelling of [123I] MIBG by a Cu(I) catalyzed reaction in aqueous solution. We regularly obtained > 99% radiochemical purity [123I] MIBG product and > 97% radiochemical yield. At 1000C with 2 mg MIBG the radiochemical purity reached 85% at 2.5 min, 97% at 5 min and 99% at 10 min through 30 min. With 200 μg MIBG the reaction proceeded at roughly one tenth the former speed. Many details of technique were essential; the highlights were use of dry triturated reagents and the use of H2SO4 solvent. Neglect of proper procedure led to low radiochemical yields and 123I bound to apparatus. The procedure has been utilized with up to 1.0 mL 123I (0.1N NaOH) or 93 mCi 123I. A study of temperature dependence showed that the reaction proceeded readily, albeit more slowly at 200C. The temperature coefficient at 1000C was estimated ∼ 1.7. (author)