Method for Removing Iodine131 from Milk

Abstract

Summary Fresh samples of raw whole milk containing iodine 131 (either added and stored for 24 hr at 4C before use, in vivo labeled, or market milk samples contaminated with fresh fallout) were passed through a column (2.0×4.8cm) containing 15ml of Dowex 2-X8 anionic resin previously charged with an aqueous solution containing NaCl, NaH 2 PO 4 , and Na 3 C 6 H 5 O 7 at pH 6.6. The concentration of each anion in the charging solution expressed in nm/liter was 4.03 (nm Cl/liter)+4.64 (nm inorganic P/liter) + 20.4 (nm citrate/liter), where the expressions in parentheses represent the composition of the milk to be treated and the numerical coefficients provide for the difference in affinity of these anions for the resin. Analysis of treated milk indicated that approximately 98±2% of I 131 was removed from 120–130 resin bed volumes of milk (and about 95% from 230 resin bed volumes). The removal of I 131 did not vary with flow rates of 5–20ml per min, and the anionic composition was essentially unchanged. Also, the rate of removal was not affected by temperatures, which ranged from 1–30C, indicating that cold temperatures may be maintained during the process, thereby minimizing bacterial growth. All the I 131 in milk was removed except the protein-bound I 131 , which was not available for ion exchange. Although the protein-bound I 131 in milk from individual cows may vary from 0–10%, it is negligible in market milk contaminated with fresh fallout. The flavor of resin-treated milk was comparable to that of untreated milk. The absorbed I 131 on the resin may be stripped with 2 n HCl prior to resin regeneration.