INDIRECT IODOMETRIC PROCEDURE FOR QUANTITATION OF SN(II) IN RADIOPHARMACEUTICAL KITS

A method of quantitating stannous ion [Sn(II)] suitable for radiopharm aceutical kits, based on indirect iodometric titration, is described. The method is based on the oxidation of Sn(II) using a known excess of iodine and the excess unreacted iodine determined using thiosulphate by potentiometric titration. The titration cell is a beaker and the ti trations are done conveniently under air using an autotitrator in appr ox. 4 min. The method is accurate and is linear in the range of approx . 10 mu g to approx. 6 mg of Sn(II). Several radiopharmaceutical kits were analysed for their Sn(II) content using the method including thos e containing antibodies or other proteins. The studies indicate that t he procedure is rapid, simple and accurate for routine quantitative es timation of Sn(II) in radiopharmaceutical preparations during developm ent, manufacture and storage.