Total Iodine Content Research Articles

Total iodine in nutritional and biological reference materials using neutron activation analysis and inductively coupled plasma mass spectrometry

In a recent collaborative study intended to extend the variety of reference materials certified for iodine, three mineralization methods were developed to quantify the total iodine content of biological and nutritional materials by inductively coupled plasma mass spectrometry (ICP-MS). A mixture of water-soluble tertiary amines was used as the matrix solution for two oxygen combustion methods and for a simple extraction at room temperature. Calibrations with matrix-matched standards, internal calibration, and isotope dilution with 129I were used. Good agreement between neutron activation analysis (NAA) and the two combustion methods was observed except for < 0.1 mg kg–1 iodine concentrations. The amine extraction method gave the most reliable results for the mixed diet, milk powder, and infant formula samples but low recoveries for other biological materials owing to an incomplete extraction and solubilization of iodine. The NAA method, with its freedom from reagent blank, is a useful technique for the independent determination of iodine in biological, environmental and food matrices, especially for verification of iodine results obtained by ICP-MS.

Effect of a Gas Bubbling and Stirring on the Oscillating Bray−Liebhafsky Reaction

A sufficient stream of nitrogen or oxygen bubbled into the oscillating Bray−Liebhafsky (BL) reaction system can suppress oscillations at ambient pressure. A significant stirring effect is observed, and it is confirmed that rapid stirring can cause the oscillatory state to be inhibited. It is shown that the rate of interphase transport of I2 can be greatly influenced by both bubbling and stirring changes. The total iodine concentration in the solution can be significantly depleted in such a way, and the value of the pseudo rate constant kobs = 3.2 × 10-4 s-1 for the I2 removal is determined to be crucial in our set up at 50 °C. This critical value of the rate constant corresponds to the mass-transfer coefficient ktr = 1.60 × 10-3 cm s-1. We suggest that the rate of transport of volatile iodine from the BL solution to the gas phase may be a significant component of the overall mechanism of the BL oscillations.

Relationship of Water Chemistry to Serum ThyroidHormones in Captive Sharks with Goitres

Captive whitetip reef sharks, Triaenodon obesus,at Sea Life Park (SLP) Hawaii, Waimanalo, Hawaii develop goitre, whereas, T. obesus at the Waikiki Aquarium (WAQ), Honolulu,Hawaii do not develop goitre. To determine theeffects of natural concentrations of iodine on thereduction of goitre, two sharks from SLP with goitrewere placed in an enclosed coastal lagoon with naturalseawater. Using ultrasound measurements the twogoitres were initially 11.4 cm and 14.6 cm in depthand after 3 months decreased to 4.7 cm and 5.7 cm. Radioimmunoassay analysis of the thyroid hormoneT3 sera concentrations were initially 0.22 ng/mland 0.33 ng/ml and increased to 1.84 ng/ml after beingplaced in the lagoon. Sera T4 were initially0.93 ng/ml and 0.99 ng/ml and increased dramaticallyto 17 ng/ml and 56 ng/ml. Over the six month samplingperiod, two resident sharks in the lagoon with normalthyroids had sera T3 concentrations from 0.89ng/ml to 1.1 ng/ml, and sera T4 concentrationsfrom 3.1 ng/ml to 7.9 ng/ml. The hypothyroidcondition in the SLP goitred-sharks is likely linkedto the low environmental iodide (<0.005 μM), andhigh nitrate (111 μM) of SLP water. The WAQwell-water facility was characterized by anoxic waterwith high iodide (0.60 μM), total iodine (1.90μM), and typical nitrate (24.6 μM)concentrations of interstitial groundwater. Thedifference of iodide concentration of SLP and WAQ tankwater (<0.005 μM versus 0.60 μM) wasdirectly related to the hydrogeology of the well-watersources. To avoid goitre in marine aquarium systems,we recommend maintaining iodide concentrations of atleast 0.15 μM.

Procedure for the determination of total iodine using automated sample preparation and ion chromatography

A Hewlett-Packard PrepStation/HPLC system has [fn1]been used to automatically process samples for the determination of total iodine. The protocol for sample preparation consists of sequentially hydrolyzing the sample, oxidizing any organic/inorganic iodo-compounds to iodate, and reduction of iodate to iodide. After preparation, liberated iodide is analyzed by ion chromatography. Selective detection of the iodide ion is accomplished using amperometric electrochemical detection at a platinum electrode. Chromatographic performance, precision, recovery, linearity, and accuracy were evaluated. The method is capable of routine determination of total iodine concentrations in the range 0.1–5 ppm total I using a single external standard but may be modified to determine concentrations outside of this range. © 1998 John Wiley & Sons, Inc. Lab Robotics and Automation 10: 19–23, 1998

Iodised rapeseed oil for eradication of severe endemic goitre

Iodised oil is traditionally based on the fatty acids (FAs) of the poppyseed, an expensive commodity. An equipotent but cheaper vehicle would be welcome. Iodination of rapeseed oil yields a product (Brassiodol) with a total iodine content of 376 mg/mL. Brassiodol has been compared with the poppyseed-based Lipiodol in two villages in Chad in the west African goitre belt. A 2 mL dose of Brassiodol is followed by urinary spillover of half the ingested iodine. The other half undergoes tissue sequestration and slow release, allowing protection against iodine deficiency for 9 months and regression of stage I/II goitre for longer than was achieved with Lipiodol. The prolonged protection offered by Brassiodol can be attributed to its unique lipid profile. The urinary output argues that 1 mL should not be exceeded, and at that dose the cost would be only 20 US cents per person per year.

Normal human intrathyroidal iodine

Excessive or deficient iodine intake results in a variety of human thyroid dysfunction and disorder. The main part in the etiology of these disorders relates to the concentrations of intrathyroidal iodine which is important to regulate thyroid function and state. Instrumental neutron activation and X-ray fluorescent analyses were used to study the age dynamics of intrathyroidal iodine. Concentration and the total content of iodine in the thyroid were estimated in necropsy samples of 70 men and 20 women aged 2–87. Both thyroid lobes were weighed, lyophilised and homogenised. Iodine was analysed in approximately 50-mg samples. The mean intrathyroidal iodine concentration (mean ± S.E.) of a normal subject aged 26–65 averaged 345 ± 21 μg g −1 dry tissue in non-endemic goitre region with no obligatory salt iodination. Maximum iodine concentration was found to be 494 ± 65 μg g −1 ( P < 0.05) for the age of 16–25. A statistically reliable second increase of iodine was shown for the elderly which was 668 ± 60 μg g −1 ( P < 0.001) for the age over 65. Human intact thyroid weight for the age over 15 does not change and averages 14.2 ± 0.4 g. Both left and right lobes of intact thyroid do not differ in weight, iodine concentration and the total content. An inverse correlation was found between thyroid weight and intrathyroidal iodine concentration (−0.32, P < 0.01). The range of intrathyroidal iodine parameters is wide enough to provide a possible explantation for the particular sensitivity of some population to both excessive and deficient iodine intake. Similarity of intrathyroidal iodine age dynamics and incidence of new cases of thyroid carcinoma were to confirm the hypothesis of intrathyroidal iodine importance in cancer etiologies suggested before.

Carbohydrate analysis of porcine thyroglobulin isoforms with different iodine contents

To further validate the relationship between thyroid hormone formation and the carbohydrate structure of thyroglobulin (Tg), we reinvestigated the relationship between the iodine content and the asparagine-linked oligosaccharide structures of porcine Tg. Purified porcine Tg was further separated into isoforms (Tg-F1, -F2 and -F3) with a DEAE–cellulose ion-exchange chromatography column. The iodine residues, neutral sugar and sialic acid were analyzed for the separated Tg isoforms and their asparagine-linked oligosaccharide structures were analyzed. The asparagine-linked oligosaccharides were released from Tg-F1, -F2 and -F3 by hydrazinolysis and each oligosaccharide was labeled with p-aminobenzoic acid octyl ester (ABOE). The ABOE-labeled oligosaccharides from Tg-F1, -F2 and -F3 were analyzed for their relative content in oligosaccharides of each structure type by chemical methods and DEAE- and ConA high-performance liquid chromatography (HPLC) columns. As a result, it was revealed that the Tg fraction eluted at higher ionic strength from a DEAE–cellulose column is apt to contain more of each iodoamino acid, as well as total content of iodine, larger negative zeta-potential, conforming to sialic acid content in the Tg molecule and to a higher content of di-sialo-bi-antennary complex and to high mannose-type oligosaccharides. These results support the conclusion that iodine organification of the Tg molecule is correlated with asparagine-linked oligosaccharide completion.

Regeneration of Inorganic Iodine Species in Loch Etive, a Natural Leaky Incubator

Iodine species concentrations and oxygen concentrations were measured in the isolated bottom waters of a Scottish fjord during two separate periods of isolation, each lasting about a year. The rates of biogeochemical change of the species were estimated by allowing for diffusive fluxes from the bottom water. This shows that iodide concentration increased during the two isolations which occurred in the study period, but that a sustained loss of iodate in the first isolation was followed by a gain during the second. Combined, these changes led to a small and gradual increase in total iodine concentration in both isolations. The iodide production is ascribed to regeneration of material with an I:C ratio of the order of 10−5in the sediment. The iodide oxidation rate is small but significant at about 0·03±0·01μMyear−1.

New approach to evaluating dissolved iodine speciation in natural waters using cathodic stripping voltammetry and a storage study for preserving iodine species

Abstract A simple and fast new method to measure dissolved total reducible iodine in natural waters using cathodic stripping voltammetry is presented here. Iodate is promptly reduced to iodide by ascorbic acid (0.5 mM) at pH ≤ 2.7, and total iodine is measured as iodide. This new method minimises possible interference and contamination from the relatively high concentration of added chemicals used in other electrochemical methods and lowers the limit of detection for iodide and total iodine to ~ 0.1 and ~ 0.2 nM, respectively, using 1 min of adsorption. This new method, as well as an adaptation of the existing electrochemical method for iodide (Luther et al., 1988), was used to determine the dissolved iodine speciation in a variety of seawater samples stored in diverse ways. The iodine speciation was preserved in samples stored for at least 2 months at −16 °C, 4 °C, and room temperature. However, after longer periods of storage (up to 1 year) at 4 °C and room temperature, iodide concentration increased up to 3 times the original value, while total iodine concentrations remained unchanged. The reduction of iodate to iodide is postulated to be bacterially mediated. Although random losses of iodide and iodate were observed in samples preserved frozen, this method, amongst those studied here, appeared to be the most suitable way of preserving iodine speciation when long-term storage is required.

Electrical activity of iodine-diffused CdTe

The electrical activity of iodine in CdTe is discussed when iodine is introduced into the CdTe by diffusion from the vapour phase. It is compared both with the total concentration of iodine in the diffused CdTe slices and with the electrical activity in CdTe slices which have been annealed under Cd- and Te-saturated vapour pressures. Iodine-diffused slices of CdTe were profiled by secondary ion mass spectrometry (SIMS) to obtain the total iodine concentration and by capacitance-voltage (C-V) techniques to obtain the net concentration of electrically active iodine. After annealing with iodine in the form of Cdl2, the slices were p-type, similar to those obtained when CdTe was annealed in either excess Te or Cd vapour, and they showed no significant increase in electrical activity. If Cd was added to the Cdl2 diffusion source or the CdTe was given a subsequent anneal in cadmium vapour, the slices became n-type. The results indicated that in all cases a neutral layer composed of Cd nIm (m and n are integers) formed on the surface layers, whereas if Cd was involved in the diffusion, some of the iodine existed in an electrically active form deeper into the slice with a maximum concentration of active carriers given by ND - NA ≈ 1017 cm−3. © 1997 John Wiley & Sons Ltd.

Measurement and Modeling of Iodine Volatility Above Irradiated Csl Solutions

Any release of radioiodine to the environment following a reactor accident depends to a large extent on its volatility within a containment structure. A common measure of iodine volatility is the water-air volumetric iodine partition coefficient (IPC), defined as the ratio of aqueous to airborne radioiodine concentrations. The impact of pH and total iodine concentration on volatility is evaluated through experiments and modeling to establish the relevant trends and improve the understanding of the underlying mechanisms. The model consists of kinetic expressions for 125 reactions. The IPC is evaluated experimentally by irradiating, at 0.25 kGy/h and 25°C, 131I-labeled CsI solutions ranging in concentration from 10−8 to 10−4 Mand in pH from 3 to 12.Both the experiments and the modeling indicate that under acidic conditions, the IPC for 10−6 M solutions is substantially higher than that for 10−5 M solutions. The predicted dependence of the IPC on pH for acidic 10−5 M solutions is in good agreement with that observed experimentally. However, substantial divergence occurred for more dilute solutions and for basic pH conditions. It is speculated that under these conditions, atomic iodine may contribute substantially to the overall volatility; adding atomic iodine volatility to the model is found to greatly improve the agreement.

Determination of the natural level of human intra-thyroid iodine by instrumental neutron activation analysis

The iodine thyroid content of 57 relatively healthy men and women 14–60 years old was studied using instrumental neutron activation analysis. Two methods were used: analysis of whole glands and the analysis of lyophilized samples weighing 50 mg each. Very good agreement between results was obtained. It was shown that the total iodine content, concentration and weight did not depend on age and sex. The typical mean thyroid parameters were found for healthy people of non-endemically goitrous regions where iodated food is not eaten. Average thyroid weight was 14.2g, iodine concentration was 350 μg/g of wet weight and thus total iodine content was 5 mg.

The variation of iodate and total iodine in some UK rainwaters during 1980–1981

A complete sequence of daily rainfall (bulk precipitation) samples collected between January 1980 and April 1981 at Wallingford, in central Southern England, together with a few month's samples from other sites in west Wales, northern England and southern Scotland, have been analysed for iodate and total iodine concentration. The wet deposition of iodine depended mainly upon the amount of rainfall, and the average monthly total iodine concentration was nnt found to vary seasonally as had been anticipated. This behaviour contrasted markedly with that of chloride and sodium ions, whose average monthly concentration decreased during summertime. On average, iodate composed one-half of the total iodine. The iodine chemistry of the rainfall is discussed in terms of the equilibrium between HOI and I2, and between iodine and other redox systems, e.g. peroxide and ozone.

Iodine desorption from rice paddy soil

Laboratory experiments on the desorption phenomena of iodine from rice paddy soil under waterlogged conditions, with a special reference to soil redox potential (Eh) and pH, have been conducted. Radioiodine tracer (1251), added to the soil, was readily sorbed on it. At the beginning of the waterlogging, the iodine desorption was low. However, iodine was desorbed into soil solution with time. The iodine desorption was enhanced markedly by the addition of organic substances such as straw pieces and glucose to the soil. Cultivation of rice plants in soil also affected the iodine desorption, suggesting root exudates and/or root autolysis might be participating in the desorption process. Eh dropped considerably after soil was waterlogged due to microbial metabolisms. Particularly low Eh values were observed in soils with plants and also with added organic substances. A negative correlation was seen between the desorption and soil Eh. High desorption was frequently observed when the Eh dropped to about -100 mV or below. Due to the reducing conditions (low Eh) by waterlogging, iodine in soil was leached into the soil solution; consequently total iodine concentration in paddy soil was considerably lower than forest and upland field soils. These iodine desorption phenomena under anaerobic conditions should be considered in assessing transfer of the long-lived radioiodine (129I) in the environment, especially in rice fields and marshland.

The distribution of dissolved iodine in hebridean waters during mid-winter

The distribution of dissolved total iodine and iodate in the waters off the Scottish coast around the Outer Hebrides in late January 1977 is described. Three types of water are delineated by the iodine results, open ocean proper, outer continental-shelf water, and coastal current water. The results confirm the sluggishness of iodide oxidation in seawater. The region between the ocean proper and the western edge of the coastal current is characterised by interconversion of iodate and iodide with little concomitant loss of total iodine. This behaviour is attributed to biological effects during the previous summer and autumn, and is seen as a general phenomenon extending along the continental margin. Implications are discussed of the finding that some of the Scottish coastal currents contained much lower concentrations of total iodine and iodate concentrations than those observed in the Irish Sea during the previous autumn.

Iodine determination in biological materials by ICP-MS

The present work describes an analytical procedure for the determination of the total iodine content in biological materials (serum, milk, plants, tissues etc.). Liquid samples can be directly analyzed after dilution, if necessary, by ICP-MS. Milk powder, plants and tissues were dissolved by using a modified simple Schoninger combustion, subsequently the residue was taken up in 0.1 mol/l NaOH and this solution was analyzed by ICP-MS. The detection limit is in the range of 0.01 μg/l. The method was tested using different CRMs certified for the iodine content.

Transformation of normal thyroids into colloid goiters in rats and mice by diphenylthiohydantoin.

Some years ago, we reported that colloid goiters could be produced experimentally in mice and rats by injection of TSH over a few days in the presence of ample iodine supply. This clearly showed that colloid accumulation and intense TSH stimulation are not mutually exclusive. In the present study, large colloid goiters, sharing many morphological and biochemical characteristics with human colloid goiters, were induced in rats and mice by treatment with 5,5-diphenyl-2-thiohydantoin (DPTH). This drug increases fecal loss of thyroid hormone and inhibits conversion of T4 to T3. Thus, DPTH raises TSH and induces macrofollicular colloid-rich goiters. In contrast to this, goiters induced by combined treatment with methimazole (MMI) or sodium perchlorate and DPTH are microfollicular, although serum TSH is increased to the same level as in rats treated with DPTH alone. The degree of iodine organification obviously determines if the follicle will sprout and form daughter follicles or if it will expand its hull. Thyroglobulin content of DPTH goiters is lower than that of normal glands but considerably higher than after MMI treatment, whereas total iodine content of DPTH goiters is only slightly lower than in normal glands, but also much higher than in MMI goiters. In DPTH goiters, a high proportion of total iodine is in the particulate fraction which probably contains the periodic acid Schiff-positive bodies floating in the colloid of DPTH treated glands. Acute DPTH administration does not inhibit iodide organification, but after treatment with DPTH for 1 day, chromatography suggests some inhibition of iodine organification and hormone synthesis by DPTH, but much less than by MMI. DPTH treatment causes considerable tissue damage and repair, such as follicular cell necrosis and invasion of the colloid by macrophages and granulation tissue. Therefore, DPTH goiters might well be a useful model not only for colloid goiter formation but also for inflammatory processes in the thyroid gland.

Systemic iodine absorption during endoscopic application of radiographic contrast agents for endoscopic retrograde cholangiopancreaticography.

Hyperthyroidism induced by contrast agents in a major problem in patients with pre-existing thyroid disease, particularly in patients with functional thyroid autonomy. The present study was undertaken to evaluate whether contrast media applied during endoscopic retrograde cholangiopancreaticography (ERCP) may result in a significant increase of serum iodine levels and thus may be associated with the risk of iodine-induced hyperthyroidism. The courses of serum concentrations of total iodine and free iodide, as well as of urinary iodine excretion, were measured in 15 patients before and up to 21 days after ERCP. During ERCP, the non-ionic contrast medium iopamidol was instilled in amounts resulting in a total iodine load of 57.4 +/- 22.8 mmol (7.3 +/- 2.9 g). In all patients, ERCP resulted in a highly significant increase in serum levels of total iodine from 0.8 +/- 0.5 to 85.2 +/- 116.9 mumol/l 4 h after application of the contrast agent. In parallel, serum iodide levels were raised from 0.06 +/- 0.04 to 5.42 +/- 6.09 mumol/l and urinary iodine excretion from 71.1 +/- 35.7 mumol/mol creatinine to 621,620.9 +/- 636,492.2 mumol/mol creatinine. Peak concentrations of serum iodine are well related to the total amount of iodine applied (p < 0.05). During follow-up, iodine levels returned to pre-exposure levels within 2-3 weeks. Levels of thyrotropin, free thyroxine, and free triiodothyronine remained unchanged during the follow-up period. In conclusion, endoscopic application of iodinated contrast agents during ERCP leads to significant increases of serum levels of total iodine and free iodide and of urinary iodine excretion.(ABSTRACT TRUNCATED AT 250 WORDS)

14. CT による甲状腺内ヨウ素濃度及び、総ヨウ素量の定量の試み〔第 2 報〕(CT-臨床)

14. CT による甲状腺内ヨウ素濃度及び、総ヨウ素量の定量の試み〔第 2 報〕(CT-臨床)

14. CT による甲状腺内ヨウ素濃度及び、総ヨウ素量の定量の試み〔第 2 報〕(第 21 回秋季学術大会一般研究発表予稿)

14. CT による甲状腺内ヨウ素濃度及び、総ヨウ素量の定量の試み〔第 2 報〕(第 21 回秋季学術大会一般研究発表予稿)