Iodine is separated from the other radioactive species by
extraction into carbon tetrachloride. Before this extraction is
made, a complete interchange must be affected between the added
iodine carrier and the tracer iodine present in the sample. The
carrier iodide (I−) is oxidized to periodate (IO4−) in alkaline
solution by NaOCl. The IO4− is reduced to I2 by hydroxylamine
hydrochloride (NH2OH•HCl) and extracted into CCl4. The I2 is
back-extracted by reduction to I− with NaHSO3. Iodide is then
precipitated as silver iodide for chemical yield measurement and
radioactivity counting. CCl4 (Note 1) Ethyl alcohol, 95% Iodine
carrier, 10.0 mg I−/mL (Note 2) HN2OH HCl, 1M NaHSO3, 0.5 M
AgNO3, 0.1 M In a 250 mL separatory funnel containing 100 mL
water sample (Note 3), add 2 mL of I− carrier solution, 2 mL of
NaOH, and 4 mL of NaOCl. Shake funnel for 2 minutes. Add 50 mL
of CCl4, 4 mL of 1M NH2OH HCl and 3 mL of conc. HNO3. Shake the
funnel for 2 minutes, and allow phases to separate.