Iodine

About: Iodine is a research topic. Over the lifetime, 8936 publications have been published within this topic receiving 139981 citations. The topic is also known as: I & element 53.

L-Cysteine as a reducing and releasing agent for the determination of antimony and arsenic using flow injection hydride generation atomic absorption spectrometry—Part 1. Optimization of the analytical parameters

Abstract: L-Cysteine was investigated as the reducing and releasing agent for the determination of antimony and arsenic using flow injection hydride generation atomic absorption spectrometry with the aim of replacing the previously used potassium iodide. The prereduction of the pentavalent to the trivalent form at room temperature was completed within 5 and 30 min for antimony and arsenic, respectively, which was essentially identical with the performance of potassium iodide. However, much lower acid and reagent concentrations were required with L-cysteine than with potassium iodide. In addition, even dilute analyte solutions containing L-cysteine were stable for at least one week, whereas solutions containing potassium iodide had to be prepared fresh daily. Under optimized conditions, in the presence of 1% m/v L-cysteine and 1 mol l–1 HCI for antimony or 0.1 mol l–1 HCI for arsenic, detection limits (three times the standard deviation of a blank solution, n= 10) of 0.05 and 0.01 µg l–1 were obtained for antimony and arsenic. The calibration graphs were linear (r > 0.999) for up to 10 µg l–1 of antimony and 5 µg l–1 of arsenic, using integrated absorbance for evaluation. The precision was better than 2% relative standard deviation (n= 10) for both elements at the 5 µg l–1 concentration level.

Iodine deficiency in vegetarians and vegans.

Abstract: Iodine content in food of plant origin is lower in comparison with that of animal origin due to a low iodine concentration in soil. Urinary iodine excretion was assessed in 15 vegans, 31 lacto- and la

Rapid regulation of thyroid sodium-iodide symporter activity by thyrotrophin and iodine.

Abstract: Transport of iodide into thyrocytes, a fundamental step in thyroid hormone biosynthesis, depends on the presence of the sodium-iodide symporter (NIS). The importance of the NIS for diagnosis and treatment of diseases has raised several questions about its physiological control. The goal of this study was to evaluate the influence of thyroid iodine content on NIS regulation by thyrotrophin (TSH) in vivo. We showed that 15-min thyroid radioiodine uptake can be a reliable measurement of NIS activity in vivo. The effect of TSH on the NIS was evaluated in rats treated with 1-methyl-2-mercaptoimidazole (MMI; hypothyroid with high serum TSH concentrations) for 21 days, and after 1 (R1d), 2 (R2d), or 5 (R5d) days of withdrawal of MMI. NIS activity was significantly greater in both MMI and R1d rats. In R2d and R5d groups, thyroid iodide uptake returned to normal values, despite continuing high serum TSH, possibly as a result of the re-establishment of iodine organification after withdrawal of MMI. Excess iodine (0.05% NaI for 6 days) promoted a significant reduction in thyroid radioiodide uptake, an effect that was blocked by concomitant administration of MMI, confirming previous findings that iodine organification is essential for the iodide transport blockade seen during iodine overload. Therefore, our data show that modulation of the thyroid NIS by TSH depends primarily on thyroid iodine content and, further, that the regulation of NIS activity is rapid.

Iodine speciation in the water column of the Black Sea

Abstract: Iodine speciation was determined on water samples collected from the upper 250 m of the Black Sea during 11–14 June 1988. Iodate, iodide and total iodine were determined by three separate voltammetric methods. In most samples, the sum of iodide plus iodate equalled the total iodine. In four samples obtained near the oxic/anoxic nonsulfidic interface, however, the sum of the iodide plus iodate was less than the total iodine (range 17–38% lower). Thus, a third form of iodine is present. Addition of sulfite to the samples did not increase the iodide concentration which would be expected if I 2 or OI − were present. It is suggested that the third form of iodine is organic and probably of high molecular weight (peptide or aromatic?). The differences with the previous results of Wong and Brewer (1977, Geochimica et Cosmochimica Acta , 41 , 151–159) can be attributed to different methods used and to differences in the water column chemistry of the Black Sea over time and perhaps season. In the previous work, O 2 and H 2 S coexisted in the zone between the oxic and sulfidic zones whereas in this work, O 2 and H 2 S were not present in the zone between the oxic and sulfidic zones.

Anodic underpotential deposition and cathodic stripping of iodine at polycrystalline and single-crystal gold: studies by LEED, AES, XPS, and electrochemistry

Abstract: The oxidative chemisorption and cathodic stripping reductive desorption of iodine have been compared at smooth polycrystalline and well-defined Au(111) single-crystal electrodes. Experimental measurements were based upon cyclic voltammetry, thin-layer coulometry, X-ray photoelectron spectroscopy, Auger electron spectroscopy, and low-energy electron diffraction. The results indicate that iodide is oxidatively adsorbed as zerovalent atomic iodine at potentials between −0.4 V and +0.4 V (Ag/AgCl reference); at lower potentials, surface iodine is reductively desorbed as aqueous iodide, while at considerably more positive potentials, it is oxidized to aqueous iodate