Iodate Concentration Research Articles

Intermittent Chaos in the CSTR Bray-Liebhafsky Oscillator-Specific Flow Rate Dependence.

Dynamic states with intermittent oscillations consist of a chaotic mixture of large amplitude relaxation oscillations grouped in bursts, and between them, small-amplitude sinusoidal oscillations, or even the quiescent parts, known as gaps. In this study, intermittent dynamic states were generated in Bray–Liebhafsky (BL) oscillatory reaction in an isothermal continuously-fed, well-stirred tank reactor (CSTR) controled by changes of specific flow rate. The intermittent states were found between two regular periodic states and obtained for specific flow rate values from 0.020 to 0.082 min−1. Phenomenological analysis based on the quantitative characteristics of intermittent oscillations, as well as, the largest Lyapunov exponents calculated from experimentally obtained time series, both indicated the same type of behavior. Namely, fully developed chaos arises when approaching to the vertical asymptote which is somewhere between two bifurcations. Hence, this study proposes described route to fully developed chaos in the Bray-Liebhafsky oscillatory reaction as an explanation for experimentally observed intermittent dynamics. This is in correlation with our previously obtained results where the most chaotic intermittent chaos was achieved between the periodic oscillatory dynamic state and stable steady state, generated in BL under CSTR conditions by varying temperature and inflow potassium iodate concentration. Moreover, it was shown that, besides the largest Lyapunov exponent, analysis of chaos in experimentally obtained intermittent states can be achieved by a simpler approach which involves using the quantitative characteristics of the BL reaction evolution, that is, the number and length of gaps and bursts obtained for the various values of specific flow rates.

Concentration of iodine in iodized salt and estimation in school meals in a region of northeast Brazil

Purpose Improper levels or excess of iodine may present a greater risk to health, for this reason, this paper aims to assess the iodine content present in salt and estimate the iodine concentration in school meals in a Brazilian northeast region. Design/methodology/approach Six samples of different salt brands sold in the city of Lagarto, Sergipe, Brazil were gathered for analyzing iodate concentration. The amounts of salt added to meals of four schools in the city and the weight of the provided meals were recorded during two consecutive days of gathering, thus obtaining data to estimate the iodine content of these meals. The rest of the meals and the nutritional composition of school meals were analyzed. A questionnaire for participants on the perception of salt was applied. For data analysis, α = 5% was used. Findings The iodine concentration in all salt samples followed legislation (15 to 45 mg of iodine/kg of salt), with the average of iodine ranged between 26.5 ± 1.29 and 33.9 ± 2.49 mg/kg (p < 0.001). The estimated iodine content in consumed school meals was 0.025 mg (25 µg), in meals of schools A and C, it was 0.03 ± 0.02 mg, and to schools B and D, it was 0.02 ± 0.01 mg (p < 0.001). Percentages of rest of the meals greater than 10% were found and the assessed food preparation showed low caloric and nutritional values. Originality/value The iodine content is in accordance with the salt iodization policy in Brazil, and that the average iodine estimate in school meals was considered adequate for this population.

Senescence as the main driver of iodide release from a diverse range of marine phytoplankton

Abstract. The reaction between ozone and iodide at the sea surface is now known to be an important part of atmospheric ozone cycling, causing ozone deposition and the release of ozone-depleting reactive iodine to the atmosphere. The importance of this reaction is reflected by its inclusion in chemical transport models (CTMs). Such models depend on accurate sea surface iodide fields, but measurements are spatially and temporally limited. Hence, the ability to predict current and future sea surface iodide fields, i.e. sea surface iodide concentration on a narrow global grid, requires the development of process-based models. These models require a thorough understanding of the key processes that control sea surface iodide. The aim of this study was to explore if there are common features of iodate-to-iodide reduction amongst diverse marine phytoplankton in order to develop models that focus on sea surface iodine and iodine release to the troposphere. In order to achieve this, rates and patterns of changes in inorganic iodine speciation were determined in 10 phytoplankton cultures grown at ambient iodate concentrations. Where possible these data were analysed alongside results from previous studies. Iodate loss and some iodide production were observed in all cultures studied, confirming that this is a widespread feature amongst marine phytoplankton. We found no significant difference in log-phase, cell-normalised iodide production rates between key phytoplankton groups (diatoms, prymnesiophytes including coccolithophores and phaeocystales), suggesting that a phytoplankton functional type (PFT) approach would not be appropriate for building an ocean iodine cycling model. Iodate loss was greater than iodide formation in the majority of the cultures studied, indicating the presence of an as-yet-unidentified “missing iodine” fraction. Iodide yield at the end of the experiment was significantly greater in cultures that had reached a later senescence stage. This suggests that models should incorporate a lag between peak phytoplankton biomass and maximum iodide production and that cell mortality terms in biogeochemical models could be used to parameterise iodide production.

Vertical and seasonal variations of dissolved iodine concentration in coastal seawater on the northwestern Pacific coast of central Japan

Vertical and seasonal variations in the concentrations of total dissolved iodine (TDI), iodide (I−), iodate (IO3−), and dissolved organic iodine (DOI) were examined for seawaters from the northwestern Pacific coast of central Japan (48 m water depth, ca. 1 km offshore) from 2012 to 2016. The annual averages of TDI and iodate concentrations in the upper layer (water depth < 10 m) were below those from deeper levels. Additionally, the concentrations decreased significantly during summer to autumn. The vertical and seasonal trends in TDI and iodate concentrations were suggested to be originated from the uptake of iodate by settling particles within the water column and partially from the input of river waters. The annual average of iodide concentration in the upper layer was higher than that in deeper levels, and the concentration tended to increase during summer to autumn. Further, the iodide concentration showed a significant positive correlation with the water temperature. The results suggest that the iodide concentration was mainly controlled by the efficiency of vertical mixing in the water column, as deeper seawater generally contains low iodide concentration. The vertical and seasonal variations in DOI concentration were erratic and thus obscured its controlling factors.

Novel Wax Valves To Improve Distance-Based Analyte Detection in Paper Microfluidics.

Microfluidic paper-based analytical devices (μPADs) have been extensively studied for disease diagnostics, food quality control, and environmental monitoring due to the advantages of low cost, portability, and simplicity. The lack of flow controllability has triggered the development of valves for such devices. This paper reports the μPADs integrating novel wax valves for distance-based detection. The valves are printed on paper and can be manually opened by organicsolvents within seconds. The opened valve does not influence the flow. The μPADs with wax valves were then applied in the distance-based detection of potassium iodate and glucose. The valves allow mixing of reagents and subsequent incubation in the loading zone, resulting in a shorter detection time and larger linear detection range. This study has demonstrated a linear detection range of 0.05-0.5 mM for potassium iodate, while linear ranges of 1-5 and 2.5-80 mg/dL are achieved for glucose when total detection time is 15 and 25 min, respectively. The lower detection limit is only 1/11 of that in a previous study. The detection ranges of iodate and glucose assays cover the concentrations of iodate in salt/milk and glucose in human saliva, respectively. Due to the simplicity, reliability, and ability for high-density integration, the μPADs with wax valves are of great potential in point-of-care (sampling) applications.

Determination of iodine level in consumer table salt from production to consumption: a cross-sectional study in occupied Palestinian territory

BackgroundIodination of table salt (salt for table use) is one of the best methods to eliminate iodine deficiency disorders (IDDs) and associated thyroid diseases. Iodate and iodide levels in table salt may vary for many reasons. There are no studies of the concentration of iodine in salt packs on the shelf and in use (open packs). This study aimed to quantify iodine in salt from twelve brands on the Palestinian market, either produced locally or imported, and both on the shelf and in use (opened). MethodsSamples of table salt (99) were collected from randomly selected market places and households in eleven governorates of the occupied Palestinian territory. From each household, three samples were collected; the first when the consumer started to use the salt package, the second when the package was half consumed, and the third when the package was almost empty. In addition, 12 salt packages were purchased from a local market, one package for each studied brand. The samples were treated and the absorbance of iodate in the sample was measured using a spectrophotometer at 665·6 nm, based on a previous method. In brief, a specific mass of salt was dissolved, then potassium iodide, hydrochloric acid, methylene blue, and acetate buffer (pH 4) were added. The solution was mixed and diluted. A reference solution using 99% sodium chloride was also created with this method. Finally, the absorbance of iodate was measured, and the iodate concentration obtained by subtracting the absorbance of the sample solution from that of the reference solution. The iodate content was then compared to the content printed on the salt package. Iodine content was also quantified for a number of samples after exposure to oven heat or being boiled or heated in water, as well as after exposure to light or dark. FindingsOf the 99 samples, 23 had lost 61% of their iodine content, 28 had lost 80%, and nine had lost all of their iodine. A little less than half (43 of 93) of the samples followed the Palestinian Standard regarding iodine content (3·5–5·5 mg per 100 g), and 70% (69 of 99) complied with the UNICEF recommendation (1·5 mg per 100 g). Iodine content in a newly opened pack (measured immediately after opening) was different from samples taken when the pack was half full, and when the pack was almost empty (0·023 mg/g, 0·0206 mg/g, and 0·0195 mg/g, respectively). The study also showed that up to 68% of iodine was lost during heating in a water solution, whereas dry heat led to a loss of 26%. Iodine loss was higher in light than in dark storage conditions (its concentration dropped from 48·2 mg/kg to 23·6 mg/kg in the dark, and decreased to 22·2 mg/kg in light). InterpretationA significant proportion of iodine is lost from salt after production and during consumption. There should be more awareness regarding the importance of using iodised salt, and education for consumers about salt storage. The iodine content in salt packages should be monitored by regulatory authorities. FundingNone.

The influence of iodate ion additions to the bath on the deposition of electroless nickel on mild steel

ABSTRACTAn alkaline hypophosphite bath (0.1 M nickel sulphate, 0.2 M sodium hypophosphite, 0.2 M sodium acetate and 0.1 M malic acid, adjusted to pH 5) was used to produce Ni–P coatings on uncoated and electroless nickel pre-plated mild steel. The deposition was monitored by open-circuit potential-time monitoring vs. a saturated calomel reference electrode and potentiostatic current–time monitoring together with anodic and cathodic polarisation. Classical mixed potential theory was applied to the polarisation data to calculate the effect of controlled iodate ion additions (0–1000 ppm) as an accelerator to the electrolyte on the plating rate. The mixed potential and deposition current density increased gradually with potassium iodate concentration. The use of electrochemical data allowed the optimum iodate additive concentration to be established using simple instrumentation.

A simple, efficient and economic method for obtaining iodate-rich chili pepper based chitosan edible thin film.

The present study was aimed at designing an iodine supplement in form of edible film made of iodate-coated chitosan (CS-IO3). Inclusion of so obtained films in diet can help in preventing thyroid cancer, leading to improved public health. Chili pepper was coated with iodate thin film (1.5µm). The iodate-rich film is ready-to-eat serving valuable nutrients. Stability studies of CS-IO3 film using water dipping revealed that there was no leaching of iodate ion, due to the strong interactions between cationic amino group of chitosan and iodate ion. The film showed no change in its antioxidant activity. Iodate concentration in the film was determined at 620nm selectively, based on the decolorization of malachite green economic method. Iodate content in fruits coated with 1.5% (w/v) CS-IO3 was 11.5mgg-1 of dry film sample. The iodate-rich samples could be stored without much effect on its freshness, indicating a good shelf life.

Intermittent Chaos in the Bray–Liebhafsky Oscillator. Dependence of Dynamic States on the Iodate Concentration

Chaotic dynamic states with intermittent oscillations were generated in a Bray–Liebhafsky (BL) oscillatory reaction in an isothermal open reactor i.e., in the continuously-fed well-stirred tank reactor (CSTR) when the inflow concentration of potassium iodate was the control parameter. They are found between periodic oscillations obtained when [KIO3]0 4.10 × 10–2 M. It was shown that the most chaotic states obtained experimentally somewhere in the middle of this region are in high correlation with results obtained by means of largest Lyapunov exponents and phenomenological analysis based on the quantitative characteristics of intermittent oscillations.

Alumina fiber-reinforced silica matrix composites with improved mechanical properties prepared by a novel DCC-HVCI method

A novel direct coagulation casting via controlled release of high valence counter ions (DCC-HVCI) method was applied to prepare the alumina fiber-reinforced silica matrix composites with improved mechanical properties. In this method, the silica suspension could be rapidly coagulated via controlled release of calcium ions from calcium iodate and pH shift by hydrolysis of glycerol diacetate (GDA) at an elevated temperature. The influence of tetramethylammonium hydroxide (TMAOH) dispersant amount, volume fraction and calcium iodate concentration on the rheological properties of suspensions was investigated. Additionally, the effect of alumina fiber contents on the mechanical properties of alumina fiber-reinforced silica matrix composites was studied systematically. It was found that the stable suspension of 50vol% solid loading could be prepared by adding 2.5wt% TMAOH at room temperature. The addition of 0–15wt% alumina fibers had no obvious effect on the viscosity of the silica suspension. The controlled coagulation of the suspension could be achieved by adding 6.5gL−1 calcium iodate and 1.0wt% GDA after treating at 70°C for 30min. Compressive strength of green bodies with homogeneous microstructure was in the range of 2.1–3.1MPa. Due to the fiber pull-out and fracture behaviors, the mechanical properties of alumina fiber-reinforced composites improved remarkably. The flexural strength of the composite with 10wt% alumina fibers sintered at 1350°C was about 7 times of that without fibers. The results indicate that this approach could provide a promising route to prepare complex-shaped fiber-reinforced ceramic matrix composites with uniform microstructure and high mechanical properties.

The potential role of kelp forests on iodine speciation in coastal seawater.

Kelps have a major role in marine and atmospheric iodine cycling in the coastal zone of temperate regions, with potential wide-ranging impacts on ozone destruction in the coastal marine boundary layer. However, little is known about the impact of kelp forests on iodine speciation in coastal sea water. To address this, we examined iodide and iodate concentrations in seawater in and around a giant kelp forest near San Diego, CA, USA, and a nearby site that was not influenced by kelp biology. Our data shows that while both iodide and iodate concentrations remained unchanged during the year at the nearby site, these concentrations changed significantly in and around the kelp forest, and were strongly related to changes in kelp canopy biomass. In particular, iodide reached its highest concentration and iodate reached its lowest concentration during the summer when the kelp canopies were near their maximum, while the opposite pattern was observed during the winter and spring when the kelp canopies were near their minimum. Further, comparisons of these changes with corresponding changes in seawater temperature and wind speed indicated that these relationships were relatively small compared to those with changes in kelp biomass. Together, our data show a strong relationship between kelp biomass and iodine metabolism.

Perspectives on Proterozoic surface ocean redox from iodine contents in ancient and recent carbonate

The Proterozoic Eon hosted the emergence and initial recorded diversification of eukaryotes. Oxygen levels in the shallow marine settings critical to these events were lower than today's, although how much lower is debated. Here, we use concentrations of iodate (the oxidized iodine species) in shallow-marine limestones and dolostones to generate the first comprehensive record of Proterozoic near-surface marine redox conditions. The iodine proxy is sensitive to both local oxygen availability and the relative proximity to anoxic waters. To assess the validity of our approach, Neogene–Quaternary carbonates are used to demonstrate that diagenesis most often decreases and is unlikely to increase carbonate-iodine contents. Despite the potential for diagenetic loss, maximum Proterozoic carbonate iodine levels are elevated relative to those of the Archean, particularly during the Lomagundi and Shuram carbon isotope excursions of the Paleo- and Neoproterozoic, respectively. For the Shuram anomaly, comparisons to Neogene–Quaternary carbonates suggest that diagenesis is not responsible for the observed iodine trends. The baseline low iodine levels in Proterozoic carbonates, relative to the Phanerozoic, are linked to a shallow oxic–anoxic interface. Oxygen concentrations in surface waters would have at least intermittently been above the threshold required to support eukaryotes. However, the diagnostically low iodine data from mid-Proterozoic shallow-water carbonates, relative to those of the bracketing time intervals, are consistent with a dynamic chemocline and anoxic waters that would have episodically mixed upward and laterally into the shallow oceans. This redox instability may have challenged early eukaryotic diversification and expansion, creating an evolutionary landscape unfavorable for the emergence of animals.

Effect of exogenous iodine on enhancement of oxidative stress in soybean (Glycine max) plant and partial expression of 1-Cys peroxiredoxin gene under heat-stress conditions

The present study analyzes the biochemical effects of exogenous iodine on the antioxidant defense system of soybean (Glycine max L.) plant when grown under heat stress (35ºC). The parameters studied under oxidative stress generation were superoxide anion production, hydrogen peroxide formation and malondialdehyde production. The enzymatic defense was investigated by analyzing the levels of superoxide dismutase, ascorbate peroxidase, catalase and glutathione reductase. For the partial expression of 1-cys peroxiredoxin, the genomic DNA was extracted and primers were designed to amplify the 3’ end region of the PER-1 gene locus 17780502 to 17781727 of genome size 61Mbp, 304 base pairs: PER1-F 5’-ATGCCAGGGATCACACTAGG-3’and PER1-R 5’-ACAAGACAGACCAAGGAGCT-3’ and subjected to PCR. The heat stress generated maximum malondialdehyde without application of iodate and production of superoxide anion was maximum in 80 µM iodate concentration. The H2O2 production was reported highest in 40 µM iodate concentration, Enzymatic defense was highest in 20 and 80 µM dosages of iodate. We amplified 1-cys peroxiredoxin (1-Cys Prx) gene, an important antioxidant enzyme, in soybean plant using primer of an Arabidopsis 1-Cys Prx gene to confer tolerance against heat stress.

Nitrate, perchlorate, and iodate co-occur in coastal and inland deserts on Earth

Deserts accumulate soluble salts from atmospheric deposition that impact human health, are a source of nutrients for organisms, and provide insight into how landscapes evolved on Earth and Mars. We quantified perchlorate, nitrate, and iodate abundances and co-occurrence in terrestrial deserts to identify fundamental controls on soluble salt deposition and post-depositional cycling. Soils and nitrate deposits were examined in Death Valley, USA; Atacama Desert, Chile; Kumtag Desert, China; and along an environmental gradient in the Transantarctic Mountains, Antarctica. Concentrations of soluble salts were highest in the Transantarctic Mountains and Atacama Desert, where stable, hyper-arid landscapes accumulate atmospheric salts over million-year time scales. Average nitrate concentrations of 61.3gkg−1 in the Transantarctic Mountains and 53.0gkg−1 in the Atacama Desert were significantly greater than respective averages of 8.60gkg−1 and 5.14gkg−1 in Kumtag Desert and Death Valley. Perchlorate and iodate concentrations in the Atacama Desert averaged 206mgkg−1 and 344mgkg−1, respectively, which were two to three orders of magnitude greater than in Antarctica and other sites. Our findings suggest that local processes in the Atacama Desert result either in higher rates of perchlorate and iodate deposition, or a greater preservation of these salts relative to nitrate when compared to Antarctic landscapes. Lower salt concentrations in the Death Valley and Kumtag Desert deposits likely result from relatively wet present-day and paleoclimatic conditions, a more active geologic history, and a greater likelihood that biocycling disrupted long-term salt accumulation. Associations of perchlorate and nitrate were significantly higher than iodate-nitrate and iodate-perchlorate correlations in the four deserts. Perchlorate-nitrate relationships ranged from insignificant to highly significant with stronger correlations in the Atacama Desert and Kumtag Desert compared to the Transantarctic Mountains and Death Valley. Weaker geochemical associations with iodate were attributed to differences in local deposition rates or post-depositional cycling. Interestingly, relationships among perchlorate, nitrate, and iodate were generally stronger when examined by site within each desert compared to analyzing the soils for each desert as a whole, suggesting more localized controls on soluble salt preservation. We conclude that soluble salts vary in concentration and type across Earth's deserts as a result of present-day environment, paleoclimate conditions, biocycling, and geologic age.

Iodine balance, growth and biochemical composition of three marine microalgae cultured under various inorganic iodine concentrations

Marine phytoplankton have been found to be involved in the biogeochemical cycle of iodine in the ocean. However, the role of iodine in the metabolism of marine microalgae has hardly been studied and whether iodine is an element required for growth is not known. In this study, three species of marine microalgae were grown in batch cultures at various concentrations of iodide (I−) or iodate (IO3 −) in order to evaluate their effect on growth rate and biochemical composition. Changes in inorganic iodine concentrations in the culture medium were also determined. Growth rate was not affected by external inorganic iodine concentration in cultures of Dunaliella salina and Tisochrysis lutea. In cultures of Phaeodactylum tricornutum, growth was inhibited at 2500 µM IO3 −. No clear effects of I− or IO3 − were observed on biochemical composition, except for the particulate iodine content of the microalgae, which increased with increasing dissolved iodine concentration. Results of dissolved inorganic iodine measurements indicated that IO3 − was reduced to I− during the exponential growth phase of microalgae cultures, under both natural and higher IO3 − concentrations. Iodine balance calculations showed that the amount of disappeared IO3 − was higher than the amount of I− produced in several cultures and that this discrepancy could not be explained by the formation of particulate iodine. I incorporation rates into biomass were low compared to I− production rates. We conclude that although iodine is clearly taken up from the external medium and it is transformed by microalgae, it seems unlikely that it is an element required for growth or that it plays an essential role in microalgal metabolism.

Determination of iodate ion in the presence of hydrogen peroxide with the stopped-flow technique

The modified titration of iodate and hydrogen peroxide with iodide in acidic medium was investigated in order to study the possibility of separation and determination of iodate under certain conditions. The stopped-flow technique was used to kinetically distinguish titration products $${\text{I}}_{ 2}$$ and $${\text{I}}_{3}^{ - }$$ formed in both reactions. Under the given conditions, the reaction between iodate and iodide is finished considerably faster than the reaction between peroxide and iodide. For the ratio [KIO3]/[H2O2] ≈ 0.08 and acidity of [H2SO4] = 1.005 × 10−1 M, the kinetic separation between both components may be achieved to within 0.3 %, in less than 3 s. The recovery value of the iodate, with the applied technique after completion of the reaction, is ≈98 % showing appropriately chosen reaction conditions. Our results show that when iodate–iodide and peroxide–iodide reactions occur simultaneously under certain conditions, the contribution of peroxide–iodide products may be neglected. It was shown that stopped-flow titration of iodate in specific reactions and certain iodate/peroxide ratio may be used for determination of iodate concentration within a few percent.

Chlorination of iodide-containing waters in the presence of CuO: formation of periodate.

It has been shown previously that the disproportionation of halogen-containing oxidants (e.g., HOCl, HOBr, and ClO2) is enhanced by a CuO-catalyzed process. In this study, the transformation of iodine during chlorination in the presence of CuO was investigated. There is no significant enhancement of the disproportionation of hypoiodous acid (HOI) in the presence of CuO. The formation rate of iodate (IO3(-)) in the CuO-HOCl-I(-) system significantly increased when compared to homogeneous solutions, which was ascribed to the activation of HOCl by CuO enhancing its reactivity toward HOI. In this reaction system, iodate formation rates increase with increasing CuO (0-0.5 g L(-1)) and bromide (0-2 μM) doses and with decreasing pH (9.6-6.6). Iodate does not adsorb to the CuO surfaces used in this study. Nevertheless, iodate concentrations decreased after a maximum was reached in the CuO-HOCl-I(-)(-Br(-)) systems. Similarly, the iodate concentrations decrease as a function of time in the CuO-HOCl-IO3(-) or CuO-HOBr-IO3(-) system, and the rates increase with decreasing pH (9.6-6.6) due to the enhanced reactivity of HOCl or HOBr in the presence of CuO. It could be demonstrated that iodate is oxidized to periodate by a CuO-activated hypohalous acid, which is adsorbed on the CuO surface. No periodate could be measured in filtered solutions because it was mainly adsorbed to CuO. The adsorbed periodate was identified by scanning electron microscopy plus energy dispersive spectroscopy and X-ray photoelectron spectroscopy.

Determination of iodate in iodized salt and water samples by shell-isolated nanoparticle-enhanced Raman spectroscopy

We have developed a simple, rapid, and sensitive method for the determination of iodate in iodized salt and water samples. The method is making use of shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) and is based on the oxidation of hydroxylammonium chloride by iodate to produce nitrite which then is used to diazotize with p-nitroaniline. The resulting diazonium ion is then coupled to N-(1-naphthyl) ethylenediamine dihydrochloride to form an azo dye whose concentration is determined by SHINERS. The active substrate used in SHINERS is composed of gold nanoparticles coated with an ultrathin silica shell possessing pinholes on their surface. Various factors that influence the chemical reaction and the intensity of SHINERS were investigated. Under the optimal conditions, the Raman intensity is linearly related to the concentration of iodate in the 7.5–130.0 μg L−1 range, with a correlation coefficient of 0.9920. The limit of detection is 2.0 μg L−1, and the relative standard deviation is 7.5 % (for n = 5) at 1,138 cm−1 without additional sample pre-concentration. The method was successfully applied to the determination of iodate in iodized salt and water samples. The accuracy was assessed through recovery tests and independent analysis by a conventional titrimetric method.

Sensitive iodate sensor based on fluorescence quenching of gold nanocluster.

In this report we described a highly selective and sensitive iodate sensor. Due to its interaction with fluorescent gold nanoclusters, iodate was capable of oxidizing and etching gold core of the nanoclusters, resulting in fluorescence quenching. Furthermore, it was found that extra iodide ion could enhance this etching process, and even a small amount of iodate could lead to significant quenching. Under an optimized condition, linear relationship between the iodate concentration and the fluorescence quenching was obtained in the range 10 nM-1 μM. The developed iodate sensor was found selective and capable of detecting iodate as low as 2.8 nM. The sensor was then applied for the analysis of iodate in real sample and satisfactory recoveries were obtained.

Formation of haloacetic acids, halonitromethanes, bromate and iodate during chlorination and ozonation of seawater and saltwater of marine aquaria systems

This manuscript addresses identification, analysis, formation and occurrence of key disinfection byproducts (DBPs) formed during chlorination and/or ozonation of both natural seawater (NSW), and synthetic high- and low-bromide saltwater (HBSW and LBSW, respectively). In this study, several groups of water disinfection byproducts were studied, including haloacetic acids (HAAs), halonitromethanes (HNMs), bromate and iodate. Three different water systems were studied including filtered natural seawater (NSW, ca. 64.9mgL−1 Br−), a high-bromide (Br−) saltwater (HBSW, ca. 24.8mgL−1 Br), and low-Br− saltwater (LBSW, ca. 4.3mgL−1Br). Because ozone reacts with Cl− to form free chlorine in seawater and salt water systems, similar DBP patterns were observed for both chlorine and ozone oxidants. The results revealed that some HAAs and HNMs are formed at greater than 100μgL−1 concentrations and are greatly affected by water constituents and formulations when treated with chlorine and ozone. The results showed that in low-Br− water salt water, chlorinated HAAs and HNMs predominated, while much greater concentrations of brominated HAAs and HNMs were produced in both natural and synthetic higher Br− saltwater. Concentrations of bromate and iodate were strongly impacted by factors other than Br− and I− concentrations including whether the system was open or closed.