Carrier-free sodium iodide

Sodium Iodide, Radioactive, Sodium iodide—,MI sodium radio-iodide (tslI) Na l iodotope Oriodide Radiocaps-131 Theriodide-131. Prepd from radioactive iodine ( l) which has a half-life of 8 days and emits beta and gamma rays. Other properties identical with those of ordinary sodium iodide. Dispensed as carrier-free sodium radioiodide in capeules for oral use Or in aq soln for oral or parenteral administration. 

Mo7, has been Isolated and measured by the recoil effect (171) An intense carrier-free sample of Mo was placed on the counting shelf of a scintillation counter for a one-minute period of growth. The aluminum front cover on the sodium Iodide crystal was not grounded but carried a potential of 500 volts negative with respect to the sample. The sample was then quickly withdrawn end the recoil daughter atoms of Ub9Qm reinaining on the front cover were counted. 

Carrier free in the form of yttrium chloride was obtained from Perkin-Elmer LAS (Belgium). Carrier free In in the form of indium chloride and 2 1 in the form of sodium iodide were obtained from Amersham (UK). Samarium-153 in the form of samarium chloride with a specific activity of 10-15 GBq/mg was obtained from the Nuclear Research Institute Rez pic (Czech Republic). 

I]Sodium iodide (carrier-free) Amersham (Buckinghamshire, UK). 

Radioactive iodine finds its widest use in the treatment of hyperthyroidism and in the diagnosis of disorders of thyroid function. Sodium iodide (lodotope Therapeutic) is available as a solution or in capsules containing essentially carrier-free suitable for oral administration. Sodium iodide is available for scanning procedures. Discussion here is limited to the uses of... 

The radiolabelling grade of radioiodine purchased from commercial suppliers will be in the form of sodium iodide. It will be essentially carrier free (i.e. uncontaminated ty stable iodine-127) and is normally dissolved in sodium hydroxide solution (typically O.Ol-O.OOl M) at concentrations of about 100 mCi (3.7 GBq)/ml. The function of the hydroxide ions are to maintain the chemical state of the iodide and prevent formation of volatile radioiodine molecules. Freshly prepared and purchased solutions of radioiodine will invariably give the best labelling efficiencies but with time, radiolysis produces free radicals which react with the iodide ions to produce non-reactive by-products. Nevertheless radioiodine solutions stored (at room temperature) for one to two months will normally give acceptable results. 

Carrier-free iodine-125 for protein iodination is available from different manufacturers in an aqueous solution containing sodium hydroxide or sodium sulfite with the activity claimed to be in the form of iodide. This may be true of freshly prepared solutions but in the course of a few weeks significant amounts of this iodide activity is transformed into unidentified species. These species may be volatile and do not exchange with added iodide even after the addition of sodium sulfite or sodium thiosulfate. The uncertainty of the chemical properties of these species essentially eliminates the direct application of chemical methods for analysis (27). Inasmuch as iodine-125 is produced by neutron-irradiation of xenon the isotopic impurities are limited to iodine-126 and iodine-127. It turns out that the total amount of iodine in an iodine-125 solution is represented primarily by iodine-125 and iodine-127 with only a negligible amount contriuted by iodine-126. The nuclides iodine-125 and iodine-127 were determined by measuring the iodine-126 and iodine-128 formed by thermal neutron activation of a sample. 

I had decayed in the target. The product was separated carrier-free by ex-traction into hexane and reduction of to iodide by sodium sulfite solution. No (from was found in the irradiated sample,... 

Iodine-136 has been separated from a solution of natural uranium which was Irradiated for 30 sec at a flux of about 5 x 10 n/cm /sec (62). Iodide carrier and sodium carbonate were added to the Irradiated solution and the iodine was oxidized with sodium hypochlorite. It was then reduced to the free state by means of hydroxylamlne In addle solution. An l2 redox cycle was then performed and elemental Iodine extracted Into carbon tetrachloride. The radio-chemical purity of the I at this stage was described as excellent. 

Most procedures for the separation of radioiodine from fission products involve the addition of iodide carrier. To insure complete exchange between added carrier and tracer, the mixture is subjected to a series of oxidation-reduction cycles. For example, in an early procedure (Procedure 15, ref. 192), iodide carrier was added to the fission product solution and oxidized to periodate by hypochlorite in alkaline solution. Periodate was reduced to molecular iodine by hydroxylamine hydrochloride in acidic solution. The iodine was extracted into carbon tetrachloride, back-extracted as iodide into water with sodium acid sulfite, and then purified by another carbon tetrachloride extraction cycle in which sodium nitrite was used for the oxidation of iodide to free iodine and sodium acid sulfite again for the reduction of iodine to iodide. 

A method claimed to be applicable for a minimum detectable activity of less than 0.05 pCI/i of sample at the time of counting has been reported (86). Carrier was mixed with the milk sample and the mixture was heated to about 75°. Iodide was collected on an anion exchange resin (resin not specified) and then eluted as lodate by means of hypochlorite. lodate was converted to free Iodine by treatment with hydroxylamlne hydrochloride and sodium nitrite. An l2"I cycle was performed and the Iodine extracted Into toluene in which medium It was determined photometrically for chemical yield. 2-Methyl butene was added to the toluene solution and the liquid sample was mixed with a toluene-based liquid scintillation counting solution and 8-gated y coincidence counting was carried out. 

In a procedure for the analysis of radioiodine In vegetation (ref. 376, pp. 94ff), the following reagents were added to the sample carrier copper foil cerlum(IV) sulfate sulfuric acid and potassium permanganate. The mixture was heated until the sample was completely oxidized. Then oxalic acid was added to convert the Iodine to the elemental form and the iodine was distilled Into aqueous sodium hydroxide. The alkaline solution was treated with hydroxylamlne hydrochloride, sodium nitrite, and nitric acid and the free Iodine was extracted Into carbon tetrachloride. The Iodine was back-extracted as Iodide with sul-furous acid and precipitated as the silver salt. 

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