Iodine speciation in size fractionated atmospheric particles by isotope dilution mass spectrometry

An isotope dilution mass spectrometric method has been developed for the accurate and sensitive determination of iodide and iodate in aerosol particles of the atmosphere. The direct iodine speciation has been possible by the use of species specifically (129)I enriched spike solutions and separation of the isotope diluted species by anion exchange chromatography after water extraction of the filters. Size fractionated collection of aerosol particles by a six stage impactor system shows different distributions of iodide and iodate for particles of different size with specific patterns for anthropogenically influenced continental and unpolluted marine aerosols, respectively. The detection limit for particulate iodide and iodate has been (3-5) pg/m(3) for sampling volumes of 3000 m(3). Oil, used for heating plants, could be identified as one but not the only anthropogenic iodine source.     

Iodine speciation in size fractionated atmospheric particles by isotope dilution mass spectrometry

An isotope dilution mass spectrometric method has been developed for the accurate and sensitive determination of iodide and iodate in aerosol particles of the atmosphere. The direct iodine speciation has been possible by the use of species specifically ¹²⁹I enriched spike solutions and separation of the isotope diluted species by anion exchange chromatography after water extraction of the filters. Size fractionated collection of aerosol particles by a six stage impactor system shows different distributions of iodide and iodate for particles of different size with specific patterns for anthropogenically influenced continental and unpolluted marine aerosols, respectively. The detection limit for particulate iodide and iodate has been (3–5) pg/m³ for sampling volumes of 3000 m³. Oil, used for heating plants, could be identified as one but not the only anthropogenic iodine source.Dedicated to Professor Dr. D. Klockow on the occasion of his 60th birthday     

Spectrophotometric determination of iodine species in table salt and pharmaceutical preparations

A sensitive spectrophotometric method for the determination of iodine species like iodide, iodine, iodate and periodate is described. The method involves the oxidation of iodide to ICl(2)(-) in the presence of iodate and chloride in acidic medium. The formed ICl(2)(-) bleaches the dye methyl red. The decrease in the intensity of the colour of the dye is measured at 520 nm. Beer's law is obeyed in the concentration range 0-3.5 microg of iodide in an overall volume of 10 ml. The molar absorptivity of the colour system is 1.73 x 10(5) l mol(-1) cm(-1) with a correlation coefficient of -0.9997. The relative standard deviation is 3.6% (n=10) at 2 microg of iodide. The developed method can be applied to samples containing iodine, iodate and periodate by prereduction to iodide using Zn/H(+) or NH(2)NH(2)/H(+). The effect of interfering ions on the determination is described. The proposed method has been successfully applied for the determination of iodide and iodate in salt samples and iodine in pharmaceutical preparations.     

Simultaneous determination of iodide and iodate in seawater by transient isotachophoresis-capillary zone electrophoresis with artificial seawater as the background electrolyte

We developed capillary zone electrophoresis with transient isotachophoresis (ITP) as an on-line concentration procedure for simultaneous determination of iodide and iodate in seawater. The effective mobility of iodide was decreased by addition of 20 mM cetyltrimethylammonium chloride to an artificial seawater background electrolyte so that transient ITP functioned for both iodide and iodate. Limits of detection for iodide and iodate were 4.0 and 5.0 microg/l (as iodine) at a signal-to-noise ratio of 3. Values of the relative standard deviation of peak area, peak height, and migration times for iodide and iodate were 2.9, 1.3, 1.0 and 2.3, 2.1, 1.0%, respectively. The proposed method was applied to simultaneous determination of iodide and iodate in seawater collected at a pond at our university.     

Simultaneous determination of fluorine and iodine in urine by ion chromatography with electrochemical pretreatment

A new method for the simultaneous determination of fluorine and iodine in urine by ion chromatography(IC) with electrochemical pretreatment has been developed.The pretreatment was performed in a novel electrochemical oxidation-neutralization device(EOND),in which iodide of the sample was oxidized to iodate and the alkaline digestion sample solution was neutralized.Under the optimized conditions,the limits of detection(LOD,S/N = 3) were 2.5μg/L for fluoride and 20μg/L for iodate,respectively.The recoverie...     

Colorimetric determination of inorganic iodine in fortified culinary products

The presented colorimetric procedure only requires simple laboratory equipment and is suitable as a routine procedure for checking concentrations of iodine in fortified culinary products. The Moxon and Dixon colorimetric procedure for iodine determination has been optimised for the determination of iodide and iodate in fortified culinary products, always containing high salt levels. The high sensitivity of the method permits a high dilution of the product solutions, thus reducing interferences from the inherent colour of the products. The calibration is linear in the range from 0 to 12 microg L(-1) of iodine with R2 > 0.99. A series of commercial culinary products were used to validate the method. Recoveries of iodine, added as iodide and/or iodate, were generally in the range 100+/-10%. High concentrations of chloride are essential to obtain a complete recovery of iodate. Limit of quantification was estimated to be 2 mg kg(-1) of product, based on 2-3 g of product. Concentrations of iodine determined with this method were similar to those obtained by an ICP-MS procedure.     

Microchemical determination of lodate and iodide in sea waters by flow injection analysis

A flow injection analysis method for iodate and iodide in sea water is described. The system involves spectrophotometric detection based on the catalytic, fading effect of either iodate or iodide on the indicator reaction of iron (III) thiocyanate and nitrite. With and without an anion-exchange column in the flow conduit, the system allows the determination of iodate and total iodine, respectively; iodide can be found by difference. Both iodate-iodine and total iodine can be determined in the range 0.75 to 150 g/1 on the sea water basis with analysis times of 20 min for iodate-iodine and 9 min for total iodine. The RSDs are within 1.3% for both iodate and iodide. Results are presented for the determination of iodate and iodide in sea waters and some brines associated with natural methane gas evolution.     

Radioanalytical studies of iodine behaviour in the environment

The behaviour of iodine in the environment is of interest both in relation to radioecology and human nutrition. Radiochemical techniques were used to evaluate various aspects of the behaviour of iodine in the environment. The natural iodine content of plant, water and soil samples collected from three sites was determined using preconcentration neutron activation analysis (PNAA). The effect of initial chemical speciation on the distribution of iodine between various soils, sediments and waters was evaluated using I-131 tracer. Iodide was found to adsorb more extensively than iodate, although for most of the solid/water systems examined, a substantial portion of the iodate was slowly reduced to iodide. Experiments involving gamma irradiation suggest that much of the sorption of iodide and reduction of iodate involved microbial processes. Distribution coefficients measured using I-131 were comparable with values based on the natural I-127 content.     

Factors affecting the serum thyroid hormone concentration during fasting in rats--with special reference to the relation with temperature

The present studies examine the effect of starvation together with cold or hot exposure on thyroid hormone levels in rats. At 23 degrees C starved for 5 days, serum thyroid hormone levels decreased significantly compared with fed rats, averaging 3.6 +/- 0.5 micrograms/dl of thyroxine (T4), 47 +/- 11 ng/dl of triiodothyronine (T3), 1.4 +/- 0.3 ng/dl of free T4 and 39.6 +/- 5.1 pg/ml of reverse T3, respectively. At 15 degrees C rats starved for 5 days, serum free T4 level significantly more increased than that of 23 degrees C starved rats, while serum T4 level and T3 did not increase significantly. At 30 degrees C rats whether concomitant starvation or not, serum thyroid hormone levels of both group markedly more decreased than control rats. These experiment provide additional evidence that thyroid gland and the peripheral metabolism of thyroid hormone respond to variety situations such as cold or hot exposure together with starvation or not.     

Measurement for serum thyroxine-binding globulin (TBG) and its clinical assessment in diagnosis of thyroid states (author's transl)]

Serum levels of thyroxine (T4)-binding globulin (TBG) were determined by a radioimmunoassay using cellulose-linked antibody to TBG. Values obtained in healthy young adults averaged 1.62 +/- 0.25 (SD) mg/100 ml, and no significant difference wwas detected between males and females. The TBG levels remained within the normal limit in hyperthyroidism while they were significantly increased in hypothyroidism. Interestingly enough, TBG levels were significantly elevated in chronic thyroidities with no overt hypothyroidism. In normal pregnancy, TBG was increased slightly in the first trimester, and markedly in the second and third trimesters. In one case of congenital TBG deficiency, no immunoreactive TBG was detected. It was demonstrated, further, that an inverse relationship (r = -0.7593) existed between the TBG level and serum triiodothyronine uptake index, and that a direct relation (r = +0.6557) was present between the TBG level and T4 in sera from normal subjects and pregnancy. Ratios of T4/TBG were markedly increased in hyperthyroidism, and decreased in hypothyroidism, showing no overlap with the normal subjects, whereas they were below the normal limit in half the cases in the second and third trimesters of pregnancy. The radioimmunoassay for TBG was useful in evaluating hypothyroid states, because it could differentiate the increase in T4 associated with elevated TBG from hyperthyroidism.     

Speciation of iodide, iodine, and iodate in environmental matrixes by inductively coupled plasma atomic emission spectrometry using in situ chemical manipulation

Dissolved iodine, iodide, and iodate are determined in environmental matrixes by in situ chemical manipulation and inductively coupled plasma atomic emission spectrometry (ICPAES). The method uses equipment commonly available to most laboratories involved in environmental inorganic analysis. Total dissolved iodine, iodide, and iodate are determined by ICPAES using iodine vapor generation. Total iodine is determined directly by ICPAES after filtration. Total dissolved iodide (I-) is oxidized in situ to iodine by the addition of sodium nitrite in sulfuric acid in a simplified continuous flow manifold. Iodate is determined by prereduction at the instrument before analysis by the in situ oxidation ICPAES procedure. A standard nebulizer produces the gas-liquid separation of the total iodine, which is then quantified by ICPAES at 206.16 nm. The instrument detection limit for the iodine analysis was 0.04 microgram/mL. Recoveries from seawater, saltwater, and freshwater standard reference materials ranged from 85 to 118% and averaged 98%. For samples containing both iodine and iodide, the total is determined with in situ oxidation, iodine is determined without the oxidizing reagents, and iodine is calculated from the difference. For samples containing all 3 species, pre-reduction is used and the iodine and iodide concentrations are subtracted for quantitation of iodate. The analysis is selective for these 3 species (I-, I2, and IO3). A group of 20-30 samples may be analyzed and quantitated for all 3 individual, commonly occurring iodide species in less than 1 h. The procedure is considerably faster than any other reported techniques. This method is especially well-suited to the analysis of small environmental samples.     

Determination of iodine and bromine compounds in foodstuffs by CE-inductively coupled plasma MS

A CE-inductively coupled plasma mass spectrometric (CE-ICP-MS) method for iodine and bromine speciation analysis is described. Samples containing ionic iodine (I(-) and IO(3)(-)) and bromine (Br(-) and BrO(3)(-)) species are subjected to electrophoretic separation before injection into the microconcentric nebulizer (CEI-100). The separation has been achieved in a 50 cm length x 75 microm id fused-silica capillary. The electrophoretic buffer used is 10 mmol/L Tris (pH 8.0), while the applied voltage is set at -8 kV. Detection limits are 1 and 20-50 ng/mL for various I and Br compounds, respectively, based on peak height. The RSD of the peak areas for seven injections of 0.1 microg/mL I(-), IO(3)(-) and 1 microg/mL Br(-), BrO(3)(-) mixture is in the range of 3-5%. This method has been applied to determine various iodine and bromine species in NIST SRM 1573a Tomato Leaves reference material and a salt and seaweed samples obtained locally. A microwave-assisted extraction method is used for the extraction of these compounds. Over 87% of the total iodine and 83% of the total bromine are extracted using a 10% m/v tetramethylammonium hydroxide (TMAH) solution in a focused microwave field within a period of 10 min. The spike recoveries are in the range of 94-105% for all the determinations. The major species of iodine and bromine in tomato leaves, salt, and seaweed are Br(-), IO(3)(-), I(-), and Br(-), respectively.     

Chemical forms of radioactive iodine in seawater and its effects upon marine organisms

Chemical forms of radioactive iodine and its effects upon marine organisms were studied by the tracer experiments. Seaweeds or fish were held in the aquarium in which the 125I tracer in either iodide or iodate form was inoculated. Iodide form of 125I was taken by Dorome (Chasmichthys gulosus) with the concentration factor of about 10 and excreted with the biological half-life of 15 days, while iodate form of 125I was not taken up appreciably and the concentration factor did not greatly exceed unity. Uptake and loss of 125I were studied as well for 3 species of seaweeds, Hijiki(Hizikia fusiforme), Nejimoku (Sargassum sagamianum) and Tsunomata (Chondrus ocellatus). Iodate form of 125I was accumulated less than iodide form by these seaweeds but the concentration factor of iodate by these seaweeds was very high compared to those by fish.     

A simplified method for the amplification of iodine

The sample solution is treated so that all iodine is present in the elemental state. This iodine is extracted into chloroform and thereby separated with very high selectivity from almost any matrix. Until now, in order to apply amplification via oxidation to iodate and reaction with iodide, a reextraction into a sodium hydroxide solution was necessary. In the new procedure the organic phase is shaken with bromine water. Thereby, the iodate formed moves completely into the water phase while the bromine accumulates in the chloroform. Remaining bromine in the water is destroyed with some formic acid. No buffer is needed, because the acid establishes the correct conditions for this reaction and also that between iodate and iodide. The iodine formed in sixfold amount can now be titrated visually or photometrically with thiosulfate or subjected to a second amplification cycle. The new procedure eliminates the reextraction, and the addition of some reagents especially sodium hydroxide which is the main contributor of extraneous iodine. Thus, the blank is reduced by a factor of 10 or more and is also more constant. Iodine at lower levels (< 1 μg/ml) can be determined and with higher reliability.     

Tracer experiments for the determination of chemical forms of radioiodine in water samples

Two simple methods, (1) isotope exchange method and (2) anion exchanger column method, are developed for the determination of chemical forms of radioiodine (iodide and iodate) in water samples. Using these methods, transformations of chemical forms of iodine in various water samples were studied. It was observed that iodate in rain water (unfiltered) and milk tended to change iodide form, whereas iodide was converted to iodate form in seawater and tap water. After the Chernobyl accident both chemical forms of¹³¹I (iodide and iodate) were found in rain water samples collected in Japan.     

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).     

Speciation of halogenides and oxyhalogens by ion chromatography-inductively coupled plasma mass spectrometry

A speciation method utilizing ion chromatography coupled with inductively coupled plasma mass spectrometry is described for simultaneous analysis of eight halogenides and oxyhalogens: chloride, chlorite, chlorate, perchlorate, bromide, bromate, iodide and iodate. The method was applied for the analysis of drinking water samples collected from water treatment plants in areas in Finland, which are known to have high bromine concentrations in ground water. Water samples collected before and after disinfection were analyzed to get information about potential species conversion as a result of purification. Chloride and chlorate were the chlorine species found in these water samples, and iodine existed as both iodate and iodide. In the case of bromine, species conversion had taken place, since total bromine concentrations were increased during disinfection but bromide concentrations were decreased. No bromate was observed in the samples. The detection limits for all the chlorine species studied were 500 μg/l, for bromine species studied 10 μg/l, for iodide 0.1 μg/l and for iodate 0.2 μg/l.     

Determination of hypophosphite and phosphite by their reduction of iodine,iodate, or periodate and mercury(I) titration of iodide

A new potentiometric method is adopted for the accurate determination of hypophosphite and phosphite alone or in their mixtures using alcoholic iodine, iodate, and periodate. Hg(I) was used as titrant for the produced iodide in case of using alcoholic iodine as oxidant or for the excess added iodide in case of iodate and periodate as oxidants using silver amalgam as the indicatior electrode. The potential breaks which average 300 mV per 0.1 ml of titrant were sharp enough for precise determination of endpoints, and hence the high accuracy of the present method.     

Development of a definitive method for iodine speciation in aquatic systems

Summary A definitive method of isotope dilution mass spectrometry (IDMS) was developed to determine four different iodine species in aquatic systems (iodide, iodate and two organoiodine compounds: one of the organic species is chromatographically elutable from a column filled with an anion exchanger resin, the other one is not). The iodine species were analysed after the isotope dilution step with an enriched ¹²⁹I spike and after their chromatographic separation. The total iodine concentration was measured after decomposition of organic compounds in the aquatic system by UV irradiation. Different types of natural water samples (river water, water of a pond, moorland lake water) were analysed and important water parameters like pH-value, redox potential, oxygen content and dissolved organic carbon were measured for each of these samples. The total iodine concentration in the different samples differed only slightly in the range of 2–7 g/l. In most of the moorland lake water samples only the two organoiodine species could be detected. In these samples the concentration of iodide and iodate was less than the detection limit of 0.5 g/l and 0.1 g/l, respectively. On the other hand, all four iodine species could be determined in most of the river water samples. Positive correlations were found for the oxygen content of the water samples and the iodate concentration as well as for the redox potential and the anionic organoiodine compound.In memoriam of Dr. I. Linus Barnes who died in January, 1990. Dr. Barnes was senior scientist at the National Institute of Standard and Technology in Gaithersburg, USA. He made numerous outstanding contributions to the field of mass spectrometry and IDMS     

Assessment of Iodine in the Diet of People Living Around a Nuclear Reprocessing Plant: Dose-Related Consequences of an Intake of 129I

It is important that in radioiodine dosimetry for low levels of daily intake, allowance must be made for the normal daily intake of stable iodine. This intake varies from one region to another, and variations are observed from one person to the next within a region, depending on eating habits. Measuring iodine in the urine over 24 hours can indirectly assess these variations. Analysis of the total iodine in the urine was carried out for 69 French people living in a temperate maritime region or in mainland France. This study justifies individual assessment of the coefficient of iodine transfer to the thyroid by means of this survey based on the urinary iodine analysis. The consequences for man of the release of ¹²⁹I around a nuclear reprocessing plant were analyzed by applying the methodology published previously by the authors. A software program based on the iodine biokinetic model recommended by the ICRP was used to calculate the daily urine excretion of ¹²⁹I for five different diets of total iodide in a ratio of 10^-4 for ¹²⁹I/¹²⁷I. This model makes it possible to set a practical detection limit of 20 mBq (0.003 µg). This approach is important from a practical point of view for health physicists involved in routine monitoring of workers in the nuclear field and members of the public exposed to radioiodine released into the environment.