Iodine-131, activity, purification

Iodine, recovery of, from silver iodide residues, 2 6, 8 Iodine-131, purification of activity of carrier-free solutions of, 6 166... 

Adsorption Method Iodine separation by the platinum adsorption technique was first reported by Toth (1961) and Lin et al. (1963). Oak Ridge National Laboratory has adopted an adsorption procedure (Case and Acree, 1966) for the purification of I produced from fission by a distillation process. In 1966, in comparison with other methods of L Baker (1966) has concluded that the adsorption technique is the most efficient and economical method. In this method, a metallic Pt plate or felt is used to adsorb carrier-free iodine from an acidic solution containing target materials. The Pt plate or felt with iodine activity is then removed from the solution and thoroughly washed with water. The activity is then desorbed in a slightly basic solution. Application of electrical current could enhance the desorption process. Nearly quantitatively the adsorbed iodine activity can be desorbed from the Pt surfaces. 

K2C03 CaH2, CaO or sodium, then fractionally distd. Near-dry alcohol can be further dried by refluxing with magnesium activated with iodine, as described for ethanol. Further purification is possible using fractional crystn, zone refining or preparative gas chromatography. 

Purification.1 Commercial KH is prepared by hydrogenation of K(0) at 230-400° several laboratories report variation in the activities of different lots. Macdonald et al.1 reasoned that the impurities could be unreduced metal or KOz. In any case, treatment of commercial KH (suspended in mineral oil) with I2 until the iodine color persists can markedly improve some reactions involving KH, in particular, the oxy-Cope rearrangement. Iodine-modified KH is also useful for in situ generation of (Bu)3SnK from KH and Bu3SnH. 

Surprisingly, the bromoperoxidases do not (like other peroxidases) oxidize organic electron donors il9,31) such as o-dianisidine or guaia-col, which are normally used to detect peroxidase activity, and thus enzymic activity easily escapes detection. When bromide or iodide are present in the assay medium HOBr and HOI are formed these reactive species will oxidize, brominate, or iodinate the organic dyes, thus allowing detection. Early in this century similar organic dyes were used to detect peroxidase activity in seaweed tissues and extracts. However, the results were not clearly reproducible. This is understandable since in seaweed variable amounts of iodide and bromide are present. On purification of the bromoperoxidase the halides are removed, resulting in an apparent decrease in or lack of activity. 

No satisfactory method has been found for removing the 3-4% of A-fraction presumably remaining in the Pentasol non-precipitated B-traction. Bates, French and Rundle have suggested that this may be removed by repeated treatment with cotton. Attempts to apply this purification have not been successful. Various grades of cotton, cellulose pulp, charcoal, activated alumina, precipitated aluminum hydroxide, bentonite and fuller s earth have been tested, without any significant improvement in the purity of the B-fraction. It is possible that Bundle s cotton treatment may introduce traces of lipid material (fatty acids or sterols) which mask the iodine adsorption. 

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