Determination of iodine in biological materials by neutron activation analysis

A method of determination of iodine (total and PBI) in serum, urine and other biological materials has been developed. The method consists in a gamma-spectrometric measurement of¹²⁸I activity after its radiochemical separation. The radiochemical separation procedure includes wet decomposition of the samples in a nitric acid medium followed by a few separation steps, the essential step being the substoichiometric extraction of iodide with a chloroform solution of tetraphenylarsonium chloride. Owing to the application of the substoichiometric separation, a high radiochemical purity of the separated iodine is achieved and the determination of the yield of radiochemical separation is not necessary.     

Comparative study of activation analyses for the determination of trace halogens in geological and cosmochemical samples.

Halogens (fluorine, chlorine, bromine and iodine) were determined by activation analyses (neutron activation analysis (NAA), photon activation analysis (PAA) and prompt gamma-ray analysis (PGA)) for geological and cosmochemical solid samples. We studied how each analytical method was for the determination of trace amounts of halogens in rock samples. Radiochemical NAA (RNAA) showed the highest analytical reliability for three halogens (chlorine, bromine and iodine), whereas a set of four halogens (fluorine, chlorine, bromine and iodine) could be determined in principle by radiochemical PAA (RPAA) from a single specimen. Although it is a non-destructive method, PGA showed an analytical sensitivity for chlorine comparable to those of RNAA and RPAA.     

Simultaneous determination of iodine and selenium in biological samples by radiochemical neutron activation analysis

Summary Regarding the favourably sensitive nuclear characteristics of iodine and of selenium but the very different half lives of their induced nuclides ¹²⁸I and ⁷⁵Se, a radiochemical neutron activation analysis method for simultaneous determination of these elements in a single sample was developed. It is based on the double irradiation LICSIR technique — Long Irradiation for Se (40h), Cooling (a week or more), Short Irradiation for iodine (1–15 min) with following Radiochemistry. After the second short irradiation, the sample is ignited in an oxygen flask and iodine and selenium are sequentially and selectively extracted as elemental iodine and 5-nitro-2,1,3 benzoselena diazole chelate. With the described method biological samples were analysed and the reliability of the results was checked by the analyses of different standard reference materials. Good agreement with certified values and high radiochemical purity of the spectra show the applicability of the radiochemical separation developed.     

Iodine in different food articles and standard reference materials

Summary The greater part of essential iodine enters living organisms via the food chain. Nevertheless, quantitative data on its concentration in diets, food articles and also in available SRMs are very poor and scarce. This and WHO recommendations on daily allowances of iodine for man via food articles caused an added demand for accurate and reliable determination of iodine in these samples. From this point of view the purpose of the present was to analyse and to establish the concentration levels of total iodine in some food articles, diets, SRMs and candidate reference materials by the use of rapid radiochemical separation, developed in our laboratory. The results were checked by the analysis of SRMs with available certified values for iodine and good agreement is evident.     

顺序注射尿碘测定仪的研制及应用

研制了一种顺序注射尿碘分析仪,将顺序注射技术与催化动力学分析相结合,利用碘对砷-铈氧化还原反应的催化作用,建立了顺序注射尿碘测定方法.采用流速和推吸可控的程控注射器及16孔程控选择阀,实现了顺序注射进样和停留稳态测量.恒温流动池使碘催化的砷-铈反应可以在恒温状态下进行.应用自行设计的微机接口电路和尿碘测定的应用软件,控制反应温度(32.0±0.1)℃,流动配送时间45 s,停流稳定时间60 s,停流检测时间20 s,进样量400 μL.本方法线性范围为15～600 μg/L,检出限为5.01 μg/L(n=11),回收率为94.1%～105.1%.对国家标准参考物质(GBW09109和 GBW09110)的测定结果在给定的标准值范围内.应用本方法检测尿碘并与国家卫生行业标准方法(WS/ T107-2006)进行比较,测定结果无显著性差异(P>0.05).     

Determination of iodine in human brain by epithermal and radiochemical neutron activation analysis

Despite the role of iodine for proper development of the brain and the functions of the element, the accurate data on its concentration in brain tissue are largely lacking, the main reason being analytical difficulties associated with determination of the element especially at low levels. In this work, samples from human brain regions from Hungarian patients were analyzed using epithermal and radiochemical neutron activation analysis (ENAA and RNAA, respectively). The RNAA procedure is based on alkaline-oxidative fusion followed by extraction of elemental iodine in chloroform. The results were checked by the analysis of biological standard reference materials, namely bovine liver, bone meal and diet, and by comparison with previous results obtained by a different RNAA procedure.     

Use of chromatographic pre-concentration for routine uranium bioassay analysis by ICP-MS

Routine monitoring of urine is an effective way to detect occupational intake of radioactive material. Historically, determinations of uranium isotopic ratios have been performed by radiochemical separation followed by alpha spectrometry. With recent advancements in technology, inductively coupled plasma-mass spectrometry (ICP-MS) has become widely available for the determination of trace metals as well as radioactive nuclides with long half-lives, such as ²³⁸U in urine. Furthermore, ICP-MS measurements of ²³⁸U do not require radiochemical separation since the number of atoms in the sample is determined instead of the number of alpha particles emitted. However, this method does not provide good sensitivity for the determination of ²³⁵U due to its shorter half-life. An improved procedure using pre-concentration of uranium and determination by ICP-MS decreases the detection limit by a factor of ten or greater with only slight increase in total analysis time. The method also has the capability of accurately determining the isotopic ratio of the sample, which is very important in cases where enriched or depleted uranium is involved.     

Iodine in mineral waters: A comparison of results from two analytical techniques

A comparative study of the determination of iodine in mineral waters is presented. Iodine was first determined by a standard titrimetric method and the results obtained were compared with those obtained by the faster and more sensitive radiochemical neutron activation method. For a series of waters, the results obtained by the two techniques were in fair agreement for the higher concentration levels of iodine, but for very low iodine levels the titrimetric method was insufficiently sensitive. The RNAA procedure was checked by standard addition experiments, and shown to be also valid when iodine was present as iodate.The paper was presented in part at the ISM XI, Wiesbaden, August 1989     

A study of the iodinated resin column for the determination of iodine in biological fluids by radiochemical neutron activation analysis

The iodinated resin technique for separation of¹²⁸I directly from neutron irradiated biological fluids is attractive due to its rapidity, simplicity and high degree of radiochemical purity; however, some doubts exist about the yields of iodine which can be recovered, particularly from organically bound iodine. In the present study, chemical yields on the resin column were studied for irradiated urine, serum and milk by standard additions of iodide and thyroxine. It was found that yields are not quantitative but lie in the range 80–95%, depending on the matrix, with a variability of up to 6% standard deviation. In addition it was shown that no significant adsorption of iodine occurs on polythene ampoules from irradiated biological fluids of natural pH. Some comparative experiments between the resin technique and the oxygen flask ignition method on fluids before or after drying, respectively, showed satisfactory agreement. It is concluded that the iodinated resin technique is suitable for routine analyses or large scale screening programs.Presented in part at SAC 83, Edinburgh, July 1983.     

Head-space flow injection for the on-line determination of iodide in urine samples with chemiluminescence detection

A simple head-space (HS) flow injection (FI) system with chemiluminescence (CL) detection for the determination of iodide as iodine in urine is presented. The iodide is converted to iodine by potassium dichromate under stirring in the closed HS vial, and the iodine is released from urine by thermostatting and is carried in a nitrogen flow through an iodide trapping solution. The concomitant introduction of aliquots of iodine, luminol and cobalt(II) solutions by means of a time-based injector into an FI system allowed its mixing in a flow-through cell in front of the detector. The emission intensity at 425 nm was recorded as a function of time. The salting-out of the standard solutions affected the gas-liquid distribution coefficient of iodine in the HS vial. The typical analytical working graphs obtained under the optimized experimental conditions were rectilinear from 0 to 5 mg l(-1) iodine, achieving a precision of 2.3 and a relative standard deviation of 1.8 for ten replicate analyses of 50 and 200 microg l(-1) iodine. However, a second-order process becomes significant at higher iodine concentrations (from 10 to 40 mg l(-1)). The detection limit of the method is 10 microg l(-1) (80 ng) iodine when 8 ml samples are taken. Data for the iodide content of 10 urine samples were in good agreement with those obtained by a conventional catalytic method, and recoveries varied between 101 and 103% for urine samples spiked with different amounts of iodide. The analysis of one sample takes less than 20 min. In the present study the iodide levels found for 100 subjects were 86.8 +/- 19.0 (61-125) microg l(-1), which is lower than the WHO's optimal level (150-300 microg per day).     

A method for estimation of Pu-isotopes in urine samples using TEVA resin and alpha spectrometry

The conventional method used for estimation of Pu-isotopes in urine samples involves anion exchange resin followed by alpha spectrometry, which takes nearly one working week for complete sample analysis. Since the results of the analysis form an important input for decision making by the plant authorities, it is always preferable to reduce overall analysis time for the estimation of Pu-isotopes in bioassay samples. This paper deals with standardization of a relatively faster method for estimation of Pu-isotopes in bioassay samples using TEVA resin and ²³⁶Pu tracer for radiochemical recovery. The method involves oxidation of urine followed by co-precipitation of plutonium along with calcium phosphate and separation of Pu was carried out using TEVA resin. Pu-fraction was electrodeposited and activity estimated using tracer recovery by alpha spectrometer. Routine urine samples of radiation workers were analyzed and consistent radiochemical tracer recovery was obtained in the range 65–87 % with a mean and SD of 75 and 7.4 %, respectively. The standardized chromatographic technique reduces the analysis time by about 1 day as compared to conventional method for estimation of Pu-isotopes in urine samples.     

Determination of plutonium isotopes in urine samples from radiation workers using <Superscript>236</Superscript>Pu tracer,anion exchange resin and alpha spectrometry

Bioassay technique is used for the estimation of actinides present in the body based on their excretion rate through body fluids. For occupational radiation workers urine assay is the preferred method for monitoring of chronic internal exposure. Determination of low concentrations of actinides such as plutonium, americium and uranium at low level of mBq in urine by alpha spectrometry requires pre-concentration of large volumes of urine. This paper deals with standardization of analytical method for the determination of Pu-isotopes in urine samples using anion exchange resin and ²³⁶Pu tracer for radiochemical recovery. The method involves oxidation of urine followed by co-precipitation of plutonium along with calcium phosphate. Separation of Pu was carried out by Amberlite, IRA-400, anion exchange resin. Pu-fraction was electrodeposited and activity estimated using tracer recovery by alpha spectrometer. Twenty routine urine samples of radiation workers were analyzed and consistent radiochemical tracer recovery was obtained in the range 74–96% with a mean and standard deviation of 85 and 6% respectively.     

Determination of uranium isotopes in urine samples from radiation workers using 232U tracer, anion-exchange resin and alpha-spectrometry

Bioassay technique is used for the estimation of actinides present in the body based on the excretion rate of body fluids. For occupational radiation workers urine assay is the preferred method for monitoring of chronic internal exposure. Determination of low concentrations of actinides such as plutonium, americium and uranium at low level of mBq in urine by alpha-spectrometry requires pre-concentration of large volumes of urine. This paper deals with standardization of analytical method for the determination of U-isotopes in urine samples using anion-exchange resin and ²³²U tracer for radiochemical recovery. The method involves oxidation of urine followed by co-precipitation of uranium along with calcium phosphate. Separation of U was carried out by Amberlite, IRA-400, anion-exchange resin. U-fraction was electrodeposited and activity estimated using tracer recovery by alpha-spectrometer. Eight routine urine samples of radiation workers were analyzed and consistent radiochemical tracer recovery was obtained in the range of 51% to 67% with a mean and standard deviation of 60% and 5.4%, respectively.     

Determination of chlorine, bromine and iodine in rock samples by radiochemical neutron activation analysis

Chlorine, bromine and iodine (hereafter, halogens) were detemined for rock samples by radiochemical neutron activation analysis. The powdered samples and reference standards prepared from chemical reagents were simultaneously irradiated for 10 to 30 minutes with or without a cadmium filter in a TRIGA-II reactor at the Institute for Atomic Energy, Rikkyo University. The samples were subjected to radiochemical procedures of halogens immediately after the irradiation. Iodine was firstly precipitated as PdI₂, and chlorine and bromine were successively precipitated as Ag-halides at the same time. In this study, geological standard rocks, sedimentary rocks and meteorites were analyzed for trace halogens. In some Antarctic meteorites, iodine contents were observed to be anomalously high. Chlorine contents also are somewhat high. The overabundance of iodine and chlorine must be caused by terrestrial contamination on the Antarctica.     

Implementation of alpha-spectrometry for uranium isotopes in excreta samples

Summary The measurement of radioactivity concentrations in excreta is an important tool for the monitoring of possible radionuclide intakes by occupationally exposed workers. For this purpose, a radiochemical procedure for the determination of alpha-emitting isotopes of uranium in excreta has been optimized. The main steps involved in this procedure are pre-concentration, dissolution of sample, separation by ion-exchange resin, electrodeposition and alpha-spectroscopy. ²³²U tracer is used to monitor chemical recoveries and correct the results to improve precision and accuracy. The quality control of radiochemical analysis in urine and faecal samples has been performed with participation in intercomparison exercises. The results obtained from these samples, with chemical recoveries (80-95%), are shown to be highly consistent. The method offers good prospects to be applied in routine monitoring programme of workers.     

Separation of131I by isotopic and non-isotopic liquid ion exchange

A study is presented on the use of isotopic and non-isotopic ion exchange in a heterogeneous liquid-liquid system for the separation of¹³¹I from water. The method is based on the reaction between radioiodide in the aqueous phase and trioctylmethylammonium iodide or chloride in the organic phase. The effect of some important experimental parameters on the separation efficiency is discussed. It has been found that under optimum conditions the method of isotopic ion exchange can be used for the radiochemical determination of iodine in water.     

Headspace single-drop microextraction coupled with gas chromatography electron capture detection of butanone derivative for determination of iodine in milk powder and urine

A new detection method using headspace single-drop microextraction (HS-SDME) coupled to gas chromatography (GC) was established to determine the iodine in milk powder and urine. The derivative from the reaction between iodine and butanone in the acidic media was extracted into a micro-drop then determined by GC-ECD. With the optimisation of HS-SDME and derivatisation, the calibration curve showed good linearity within the range of 0.004–0.1 μg mL^?1 (0.004–0.1 μg g^?1) (R ² = 0.9991), and the limits of detection for milk powder and urine were 0.0018 μg g^?1 and 0.36 μg L^?1, respectively. The mean recoveries of milk powder and urine were 90.0–107 % and 89.4–101 % with mean RSD of 1.7–3.4 % and 2.7–3.3 %, respectively. This detection method affords a number of advantages, such as being simple, rapid, and inexpensive, with low organic solvent consumption, and is remarkably free from interference effects, rendering it an efficient method for the determination of iodine in milk powder and urine samples.     

Kinetic determination of total iodine in urine and foodstuffs using a mixed acid as a pretreatment agent.

An analytical method for the determination of total iodine at the ng level in urine, biological materials and foods was investigated. The organic substances were completely decomposed using a mixed solution of nitric, perchloric and sulfuric acids as pretreatment agents at ca. 230 degrees C. Iodine in the resulting solution was analyzed by a kinetic-photometric method based on the catalytic effect of iodine on the oxidation of chlorpromazine by hydrogen peroxide. The relative standard deviation was 1.6% for 100 ng of iodide and the detection limit of the method was 1.6 ng (3sigma). The proposed method was successfully applied to the determination of iodine at ng levels in real samples.     

Determination of mercury in human urine by neutron activation analysis,with lead diethyldithiocarbamate as a preconcentration agent

Lead diethyldithiocarbamate is an effective reagent for preconcentration of mercury in urine for neutron activation analysis. Sodium and bromine are removed from the sample by this procedure. As lead diethyldithiocarbamate is insensitive to neutron activation, radiochemical separation is not needed after neutron irradiation. Results from the analysis of urine collected from workers in caustic soda manufacturing plants are discussed.     

Separation and determination of <Superscript>241</Superscript>Am in urine samples from radiation workers using PC88-A and alpha spectrometry

Bioassay technique is used for the estimation of actinides present in the body based on their excretion rate through body fluids. For occupational radiation workers urine assay is the preferred method for monitoring of chronic internal exposure. Determination of low concentrations of actinides such as plutonium, americium and uranium at low level of mBq in urine by alpha spectrometry requires pre-concentration of large volumes of urine. This article deals with standardization of analytical method for the determination of ²⁴¹Am isotope in urine samples using Extraction Chromatography (EC) and ²⁴³Am tracer for radiochemical recovery. The method involves oxidation of urine followed by co-precipitation of americium along with calcium phosphate. This precipitate after treatment is further subjected to calcium oxalate co-precipitation. Separation of Am was carried out by EC column prepared by PC88-A (2-ethyl hexyl phosphonic acid 2-ethyl hexyl monoester) adsorbed on microporous resin XAD-7 (PC88A-XAD7). Am-fraction was electro-deposited and activity estimated using tracer recovery by alpha spectrometer. Ten routine urine samples of radiation workers were analyzed and consistent radiochemical recovery was obtained in the range 44–60% with a mean and standard deviation of 51 and 4.7% respectively.