Radiochemical analysis, of iodine

Radioiodine plays an important role in the diagnosis and treatment of various thyroid disorders. Production methods for various iodine isotopes, namely, and are briefly described in this paper. The chemistry of iodine and radiation effects in aqueous solutions and isotopic exchange reactions are also reviewed. An understanding of the chemistry of iodine is essential in isotope production, and for developing the procedure to prepare the radioactive iodine labeled pharmaceuticals. In radiochemical analysis of iodine, most environmental and biological samples can be accurately analyzed by neutron activation at trace levels. The use of potassium iodide (KI) has become an important remedy to prevent the harmful effects of radioiodine exposure under nuclear accident conditions. The inhibitory effect of KI administration on thyroid radioactive iodine uptake is discussed. 

Brauer, F.P. and Kaye, J.H. (1974). Detection systems for the low-level radiochemical analysis of iodine-131, iodine-129, and natural iodine in environmental samples, IEEE Trans. Nucl. Sci. 21,446. 

Brauer, F. P. and Kaye, J. H. Detection Systems for the Low-Level Radiochemical Analysis of Iodine-131, Iodine-129, and Natural Iodine In Environmental Samples. IEEE (Inst. Elec. Electron. Eng.), Trans. Nucl. Scl. NS-iL. No. 1, 496 (1974). 30 5867... 

The behavior of iodine at trace levels is often anomalous compared with that at macro concentrations. Because of these anomalies, in radiochemical investigations of iodine, either trace analysis or synthesis of labeled compounds, care must be taken to develop proper procedures to deal with potential problems. At the beginning of this review, it is necessary to briefly discuss the major chemical reactions of iodine, which are of importance to radiochemical studies and may be involved in chemical analysis and isotope production. Also included in this discussion are... 

The analysis of iodine at trace levels is reviewed in detail. Classical radiochemical procedures commonly been used in various samples, but neutron activation is probably more popular in environmental and biological samples. Gamma-spectrometric methods are often used in conjunction with Nt A. 

Dermelj M and Byrne AR (1997) Simultaneous radiochemical neutron activation analysis of iodine, uranium and mercury in biological and environmental samples. Journal of Radioanalytical and Nuclear Chemistry 216 13-18. 

The analysis of trace iodine in biological, as well as environmental, samples is of immense interest in this review. Special attention is given to the radiochemical analysis with neutron activation of I and I. 

Chemical analysis of trace iodine, in either biological or environmental samples, always encounters problems of interference from impurities and uncertainty in chemical yield of analysis. As discussed previously in Chemistry of Iodine Relevance to Radiochemical Studies and Nuclear Properties of Iodine Isotopes , the chemistry of iodine is very complex and isolation or purification of iodine from the sample is a major obstacle in a traditional chemical analysis. 

Accuracy of the applied techniques - radiochemical neutron activation analysis for iodine (I) and instrumental neutron activation analysis for Br and Cl determination - was checked by analysis of the National Institute of Standards and Technology (NIST) SRMs. Our values were compared with the recommended values of NIST SRMs Catalog (1990). 

Radiochemical methods of analysis can be grouped according to whether one measures radioactivity present in the sample or employs some means of introducing radioactivity into an otherwise nonradioactive sample in order to analyze for some component. An example of the first type is the determination of radioactive in rock samples. The second type is exemplified by using labeled KPO3 (I denoting a radioisotope of iodine) to determine the concentration of SO2 in air by the radiorelease method. This chapter will deal with the use of radioactivity to analyze otherwise nonradioactive substances. 

Determination of Chemical Species of Iodine in Seawater by Radiochemical Neutron Activation Analysis Combined with Ion-Exchange Presejraration. Anal. Chem., Vol.71, No. 14, pp 2745-2750, ISSN 0003-2700... 

Petri, H. and Erdtmann, G. Microdetermination of Iodine in [Bi-p-iodophenylalanine] Insulin by Neutron Activation Analysis. Radiochem. Radioanal. Lett. , No. 4, 309 (1972). 26 22552... 

Photoactivation analysis has also been used to determine fluoride in seawater [73]. In this method a sample and simulated seawater standards containing known amounts of fluoride are freeze-dried, and then irradiated simultaneously and identically, for 20 min, with high-energy photons. The half-life of 18F (110 min) allows sufficient time for radiochemical separation from the seawater matrix before counting. The specific activities of sample and standards being the same, the amount of fluoride in the unknown may be calculated. The limit of detection is 7 ng fluoride, and the precision is sufficient to permit detection of variations in the fluoride content of oceans. The method can be adapted for the simultaneous determination of fluorine, bromine, and iodine. 

Accelerator mass spectrometry (AMS) is useful to measure extremely low-abundance nuclides (isotope ratio of 10 to 10 relative to its stable isotope), such as Be, C, A1, C1, " Ca, and I, in natural samples. Small amounts of C and T can be measured by AMS on mg size samples of carbon and iodine extracted from 500-ml seawater samples (Povinec et al. 2000). Neutron activation analysis (NAA), radiochemical neutron activation analysis (RNAA), and inductively coupled plasma mass spectrometry (ICP-MS) are useful for the determination of ultra-trace Th and U in geological and cosmochemical samples, and for determination of the concentration of Pu and Pu. Reference marine-biological samples are necessary to test the performance of the analytical methods employed in surveying and monitoring radioactive materials in the sea. An ocean shellfish composite material containing 0.1% w/w Irish Sea mussel, 12% w/w White Sea mussel, and 87.9% w/w Japan Sea oyster has been prepared as the NIST SRM 4358 (The National Institute of Standards and Technology, SRM) in the natural-matrix, environmental-level radioactive SRM series (Altzitzoglou 2000). This NIST SRM 4358 sample will be useful for the determination of the activity of K, Cs, Pb, Ra, Th, and Am. 

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