Iodide In Seawater Research Articles

Separation of iodate, bromide, nitrite, nitrate, and iodide in seawater by ion chromatography using 1-aminoundecyl group chemically bonded silica columns.

The separation and detection of six common inorganic anions (iodate (IO3-), bromate (BrO3-), bromide (Br-), nitrite (NO2-), nitrate (NO3-), and iodide (I-)) in pure water and 35 ‰ artificial seawater were examined by ion chromatography (IC). As packing materials of separation columns, 1-aminoundecyl group chemically bonded silica (AUS) gels were prepared. Separation of the anions in pure water was achieved using separation columns (150mm × 4.6mm i.d.) packed with the AUS gels, 0.1M NaCl + 5mM phosphate buffer (pH 4.5) as eluent, and a UV detector (wavelength 225nm). The anions in artificial seawater were separated and detected with a 300mm-long column without interferences by matrix anions such as chloride (Cl-) and sulfate (SO42-). The stationary phases have high-capacity anion-exchange/hydrophilic/hydrophobic interaction mixed-modes. The IC system was applied to five inorganic anions, IO3-, Br-, NO2-, NO3-, and I- in seawater of the Seto-Inland Sea, Japan. The detection limits (DLs, S/N = 3) were 11µgL-1 (IO3-), 93 (Br-), 1.3 (NO2-), 1.4 (NO3-), and 1.1 (I-) for a 100-µL sample injection.

A Multi-Sensor System for Sea Water Iodide Monitoring and Seafood Quality Assurance: Proof-of-Concept Study.

Iodine is a trace chemical element fundamental for a healthy human organism. Iodine deficiency affects about 2 billion people worldwide causing from mild to severe neurological impairment, especially in children. Nevertheless, an adequate nutritional intake is considered the best approach to prevent such disorders. Iodine is present in seawater and seafood, and its common forms in the diet are iodide and iodate; most iodide in seawater is caused by the biological reduction of the thermodynamically stable iodate species. On this basis, a multisensor instrument which is able to perform a multidimensional assessment, evaluating iodide content in seawater and seafood (via an electrochemical sensor) and discriminating when the seafood is fresh or defrosted quality (via a Quartz Micro balance (QMB)-based volatile and gas sensor), is strategic for seafood quality assurance. Moreover, an electronic interface has been opportunely designed and simulated for a low-power portable release of the device, which should be able to identify seafood over or under an iodide threshold previously selected. The electrochemical sensor has been successfully calibrated in the range 10–640 μg/L, obtaining a root mean square error in cross validation (RMSECV) of only 1.6 μg/L. Fresh and defrosted samples of cod, sea bream and blue whiting fish have been correctly discriminated. This proof-of-concept work has demonstrated the feasibility of the proposed application which must be replicated in a real scenario.

Poly(ethylene glycol) Methyl Ether Methacrylate-bonded Stationary Phase in Ion Chromatography and Its Application to Seawater Samples.

A fast and simple ion chromatographic method for the determination of iodide in seawater is reported using poly(ethylene glycol) methyl ether methacrylate-bonded stationary phase. Poly(ethylene glycol) methyl ether methacrylate was reacted with primary amino groups of aminopropylsilica in N,N-dimethylformamide at 80°C. The prepared stationary phases were evaluated by analyzing several inorganic anions and the retention behavior was observed. Various chromatographic parameters were optimized for the separation of these anions. Although there were no ion-exchange sites on the resulted stationary phases, the results obtained suggested that an ion-exchange mechanism was involved in the retention of analyte anions. With 0.15 μL injection, the limit of quantitation of iodide was 26 μg L-1 when 200 mM NaCl was selected as the eluent. This stationary phase was applied to the analysis of direct and fast determination of iodide in real seawater samples successfully with the recovery rates of 98.1 and 104.9%.

Photoluminescent nanopaper-based microcuvette for iodide detection in seawater

Nanopaper defined as a sheet made of cellulose nanofibers has recently attracted a growing interest in paper-based flexible and transparent sustainable transistors, electronics, devices and sensors. Use of bacterial cellulose nanopaper, particularly in optical sensing platforms, is becoming increasingly popular owing to its numerous desirable properties. Herein, we propose a carbon quantum dots-embedded paper-based sensor for selective iodide sensing. To this aim, the nanopaper was obtained by an environment-friendly approach using bacterial cellulose made of nanofibers (the diameter of nanofibers was observed as 40±10nm), which were produced by A. xylinum. Then, nitrogen-doped carbon quantum dots were embedded into nanopaper to gain photoluminescence properties. The obtained photoluminescent nanopaper was cut into circular pieces for easily handling, or rectangular pieces for use in a disposable wax-printed paper-based microcuvette which could be inserted in a common spectrofluorometer. Finally, the nanopaper pieces were used for anion sensing and we obtained a selective detection of iodide in seawater (as a model real sample media). Limit of detection (LOD) and limit of quantification (LOQ) values were respectively calculated as 48 and 144μM (6.1 and 18.3ppm) for microcuvette application in seawater.

Determination of iodide and total iodine in estuarine waters by cathodic stripping voltammetry using a vibrating silver amalgam microwire electrode

Iodide in natural waters is an important nutrient to aquatic organisms and its determination is of relevance to marine aquaculture. For this reason it is of interest to have a simple analytical method for determination of iodide in water samples. Iodide in seawater can be determined electrochemically by cathodic stripping voltammetry (CSV) with a mercury drop electrode which has environmental drawbacks. In an attempt to minimise the use of mercury in voltammetry, a vibrating silver amalgam microwire electrode is used here for the determination by CSV of iodide speciation in natural waters including seawater. Microwire electrodes were made from silver wires (diameter: 12.5µm) and electrochemically coated with mercury. The electrode surface was stable for extended periods of analyses (at least one week) and was then replaced. The optimised conditions include a pH 8, a frequency of 500Hz and a deposition time of 60s, among others. The microwire was reactivated between scans using a conditioning potential at −3 V for 1s. The detection limit for iodide in seawater was found to be 0.7nM I- at a deposition time of 60s. The response increased linearly with the concentration of iodide in seawater up to 100nM I-. The method was successfully applied to various samples from the estuary of the river Mersey (Liverpool Bay). An existing procedure for iodine speciation was modified to enable determination of iodate and total iodine as well as iodide in estuarine waters.

A portable multi-syringe flow system for spectrofluorimetric determination of iodide in seawater

A miniaturized analyzer encompassing a poly(methyl methacrylate) chip with integrated spectrofluorimetric detection and solutions propelling by a multi-syringe module is proposed. Iodide was determined through its catalytic effect on the reaction between Ce(IV) and As(III). Matrix isopotential synchronous fluorescence was explored to set the excitation and emission wavelengths. A two-level full factorial design allowed to evaluate the significance of variables (Ce(IV), As(III) and H2SO4 concentrations) and their interaction effects in the experimental domain. A Doehlert Matrix was applied to identify the critical values. The optimized procedure showed a linear response from 1 to 100μgL−1 (S=53.7+2.61C, in which S is the net fluorescence and C is iodide concentration in μgL−1). Detection limit, coefficient of variation (n=6) and sampling rate were estimated at 0.3 μgL−1, 0.8% and 20h−1, respectively. Recoveries within 90–117% were estimated for iodide spiked to seawater samples. The proposed procedure stands out because of the portability, robustness, and simplicity for in-field analysis of iodide in seawater.

Impact of Enhanced Ozone Deposition and Halogen Chemistry on Tropospheric Ozone over the Northern Hemisphere

Fate of ozone in marine environments has been receiving increased attention due to the tightening of ambient air quality standards. The role of deposition and halogen chemistry is examined through incorporation of an enhanced ozone deposition algorithm and inclusion of halogen chemistry in a comprehensive atmospheric modeling system. The enhanced ozone deposition treatment accounts for the interaction of iodide in seawater with ozone and increases deposition velocities by 1 order of magnitude. Halogen chemistry includes detailed chemical reactions of organic and inorganic bromine and iodine species. Two different simulations are completed with the halogen chemistry: without and with photochemical reactions of higher iodine oxides. Enhanced deposition reduces mean summer-time surface ozone by ∼3% over marine regions in the Northern Hemisphere. Halogen chemistry without the photochemical reactions of higher iodine oxides reduces surface ozone by ∼15% whereas simulations with the photochemical reactions of higher iodine oxides indicate ozone reductions of ∼48%. The model without these processes overpredicts ozone compared to observations whereas the inclusion of these processes improves predictions. The inclusion of photochemical reactions for higher iodine oxides leads to ozone predictions that are lower than observations, underscoring the need for further refinement of the halogen emissions and chemistry scheme in the model.

A miniaturized analyzer for the catalytic determination of iodide in seawater and pharmaceutical samples

A monolithic flow conduit was especially designed and coupled to a multisyringe unit (MSFIA) in order to develop a kinetic analytical method. The new device, denoted CHIP, integrates different functions in a reduced size including confluent mixing, reaction coil, and thermostating, which allowed minimizing the dimensions of the entire analyzer system. The CHIP–MSFIA was satisfactorily applied to the determination of iodide using the Sandell–Kolthoff reaction. The resulting system allows fast, simple and automatic analysis in seawater samples and a pharmaceutical preparation. By the use of an additional syringe, reagent blank, sample blank, unspecific interferences, and sample analyte concentration was evaluated by simply changing the mode of operation. The instrumentation and analytical procedures were optimized in respect of sensitivity. A limit of detection of 4.7μgL−1 and linear working range of 4.3–70μgL−1 were achieved.Two new modes of air bubble elimination were developed and employed in this work, leading to improved reproducibility (RSD %=1.5%) and method robustness. The accuracy of analysis for seawater samples was evaluated by an Add–Recovery test obtaining recoveries between 97 and 106%. For the quantification of iodide in the pharmaceutical sample, standard addition calibration was required. No significant differences between the found and the certified value were found. The entire analytical procedure lasted about 150s enabling a measuring frequency of 23h−1.

Determination of Iodide in Seawater by Capillary Ion Chromatography Using Hexadimethrine Bromide Modified C30 Stationary Phases

A novel and simple capillary ion chromatographic method for the determination of iodide is reported. Separation was achieved on a laboratory-made packed capillary column (100 mm × 0.32 mm i.d.) packed with triacontyl-functionalized silica, followed by a modification with hexadimethrine bromide, where 1 mM sodium chloride-acetonitrile (95:5, v/v) was used as the eluent and UV-absorbing analyte anions were detected at 225 nm. The effects of the eluent composition on the retention behavior of inorganic anions were investigated. The addition of a small amount of an organic substance in an eluent such as acetonitrile increased the retention of iodide, while the addition of methanol decreased its retention. The present analytical method was successfully applied to the rapid and direct determination of iodide in seawater without any preconcentration. Also, this modified column could be used for about two months (6 h operation per day) without hexadimethrine bromide being contained in the eluent.

Rapid determination of iodide in seawater samples by ion chromatography with chemically-bonded vitamin-U stationary phase

A simple and rapid analytical method using a laboratory-made packed column (100mm×0.32mm i.d.) was developed for the determination of iodide in seawater. The stationary phases were prepared by the reaction of the hydroxyl group on the surface of the diol-group bonded silica gel with vitamin U. Simultaneous separation of four common inorganic anions (iodate, nitrate, iodide, and thiocyanate) was achieved within 9min using 0.05mM sulfuric acid–methanol (99:1, v/v) as the eluent. The limit of detection of iodide was 8.2μgl−1 (S/N=3), and the limit of quantification was 27μgl−1 (S/N=10). The RSD values of retention time, peak area and peak height were all smaller than 2.4%. The present analytical method was successfully applied to the rapid and direct determination of iodide in seawater samples collected from Japan coasts, and gave iodide content from 46.8 to 54.1μgl−1, by using a standard addition method. The recoveries of added iodide were from 95.6 to 106.4%. In the present system, the retention of analytes may not be caused by electrostatic interaction, but by hydrophobic interaction.

Determination of nitrite, nitrate, bromide, and iodide in seawater by ion chromatography with UV detection using dilauryldimethylammonium-coated monolithic ODS columns and sodium chloride as an eluent

A method was developed for determination of inorganic anions, including nitrite (NO(2)(-)), nitrate (NO(3)(-)), bromide (Br(-)), and iodide (I(-)), in seawater by ion chromatography (IC). The IC system used two dilauryldimethylammonium bromide (DDAB)-coated monolithic ODS columns (50 × 4.6 mm i.d. and 100 × 4.6 mm i.d.) connected in series for separation of the ions. Aqueous NaCl (0.5 mol/L; flow rate, 3 mL/min) containing 5 mmol/L phosphate buffer (pH 5) was used as the eluent, and detection was with a UV detector at 225 nm. The monolithic ODS columns were coated and equilibrated with a 1-mmol/L DDAB solution (in H(2)O/methanol, 90:10 v/v). The hydrophilic ions (NO(2)(-), NO(3)(-), and Br(-)) were separated within 3 min and the retention time of I(-) was 16 min. No interferences from matrix ions, such as chloride and sulfate ions, were observed in 35 ‰ artificial seawater. The detection limits were 0.6 μg/L for NO(2)(-), 1.1 μg/L for NO(3)(-), 70 μg/L for Br(-), and 1.6 μg/L for I(-) with a 200-μL sample injection. The performance of the coated columns was maintained without addition of DDAB in the eluent. The IC system was successfully applied to real seawater samples with recovery rates of 94-108 % for all ions.

Iodine to calcium ratios in marine carbonate as a paleo-redox proxy during oceanic anoxic events

Periods of globally distributed extreme oxygen depletion, so-called oceanic anoxic events (OAEs), have been recognized in the Mesozoic geological record and appear to be characteristic of episodes of extreme warmth. Here we explore the application of iodine/calcium ratios (I/Ca) in marine carbonate as a new geochemical proxy to constrain seawater redox change, and provide additional insights into the response of ocean chemistry to ancient climatic warming. Iodine has long been known as a redox-sensitive and biophilic element, mainly present as iodate and iodide in seawater, iodate converting to iodide under anoxic conditions. Laboratory experiments growing calcite crystals from solutions spiked with iodate show that this is the ionic species incorporated into the carbonate structure, likely substituting for the CO 3 2− ion. A fall in the I/Ca ratio measured in carbonates formed in shallow water by marine calcifiers during the early Toarcian and Cenomanian-Turonian OAEs is interpreted both as a response to a decrease in the iodate/iodide ratio in ocean waters and the drawdown of the global iodine inventory under conditions of accelerated organic-matter burial. The results suggest that I/Ca ratios in carbonates may be used to monitor seawater oxidation levels throughout Earth history.

Addressing Widespread Iodine Deficiency Disorders: A Serious Health Problem in Thailand and Beyond

Iodine is the heaviest of all elements essential for human health. Iodine is a constituent of the thyroid hormone that acts on many body systems, and thus, iodine’s effects are quite broad. In discussing iodine deficiency disorders (IDDs), one should rank mental defects and physical impairments ahead of goiter, which is a mere physical disfigurement. Consuming iodide- or iodate-supplemented salt has been the most widely implemented public health measure for people at risk of iodine deficiency. However, millions of people on several continents still suffer today from insufficient iodine intake. Inadequate government enforcement and limited access to supplemented salt are partly responsible for the persistence of this disease. Traditional beliefs and food habits are also contributing factors toward difficulties in lowering the incidence and severity of IDDs. In the multistep process needed for making dry salt, most iodide in seawater is converted to iodine, which sublimates, thus drastically reducing the iodine content. Regular consumption of iodized table salt is a necessity for people, especially those at risk of developing IDDs.

Disinfection by-products and their potential impact on the quality of water produced by desalination systems: A literature review

When chemical disinfection is applied before or after desalination systems, compounds may be formed that pose potential risks to the health of human and aquatic organisms or impact aesthetic quality of drinking water. The formation and speciation of disinfection by-products (DBPs) in desalination systems is affected by the elevated concentrations of bromide and iodide in seawater and desalinated product water. To gain insight into DBPs likely to be formed in desalination systems, DBP studies conducted in saline source waters, coastal power stations and existing desalination systems are reviewed. Chlorination is the most common disinfectant used in current desalination systems, with chloramines and chlorine dioxide gaining more popularity for disinfection of desalinated water. When seawater or reverse osmosis permeate is chlorinated, bromoform (CHBr 3) and brominated haloacetic acids (e.g. monobromoacetic acid, dibromoacetic acid, bromochloroacetic acid) are found to be the prevalent DBP species. Under conditions typically encountered in desalination systems, concentrations of these DBPs in the product drinking water are below levels of concern set by regulating agencies. Less information is available on the formation of other haloorganic DBPs in desalination plants. Among DBPs identified in saline drinking waters, haloacetonitriles (HANs), mutagen X compounds (MX), halonitromethanes (HNMs) and cyanogens bromide (CNBr) pose potential concerns, especially when desalinated waters are blended with organic-matter rich source waters.

The biogeochemical effect of seaweeds upon close-to natural concentrations of dissolved iodate and iodide in seawater – Preliminary study with Laminaria digitata and Fucus serratus

Toward assessing the biogeochemical significance of seaweeds in relation to dissolved iodine in seawater, the effect of whole seaweeds ( Laminaria digitata and Fucus serratus) upon iodide and iodate, at essentially natural concentrations, has been studied. The weeds were carefully removed from the sub-littoral zone of the Menai Straits and exposed to iodide and iodate at their natural temperature (6 °C), but under continuous illumination. Laminaria digitata was found to decrease the concentration of iodate with an exponential rate constant of 0.008–0.24 h −1. This is a newly discovered process which, if substantiated, will require an entirely new mechanism. Generally, apparent iodide concentration increased except in a run with seawater augmented with iodide, where it first decreased. The rate constant for loss of iodide was 0.014–0.16 h −1. Meanwhile, F. serratus was found not to decrease iodate concentrations, as did L. digitata. Indeed, after ∼30 h iodate concentrations increased, suggesting that the weed may take in iodide before oxidising and releasing it. If substantiated, this finding may offer a way into one of the most elusive of processes within the iodine cycle – iodide oxidation. With both seaweeds sustained long-term increases of apparent iodide concentration are most easily explained as a secretion by the weeds of organic matter which is capable of reducing the Ce(IV) reagent used in determination of total iodine. Modelling of the catalytic method used is provided to support this contention. The possibility of developing this to measure the strain that seaweeds endure in this kind of biogeochemical flux experiment is discussed. A Chemical Oxygen Demand type of approach is applied using Ce(IV) as oxidant. The results of the iodine experiments are contrasted with the several investigations of 131I interaction with seaweeds, which have routinely used discs of weed cut from the frond. It is argued that experiments conducted with stable iodine may measure a different variable to that measured in radio-iodine experiments.

Speciation of iodate and iodide in seawater by non-suppressed ion chromatography with inductively coupled plasma mass spectrometry

A non-suppressed ion chromatography (IC) with inductively coupled plasma mass spectrometry (ICP-MS) has been developed for simultaneous determination of trace iodate and iodide in seawater. An anion-exchange column (G3154A/101, provided by Agilent) was used for the separation of iodate and iodide with an eluent containing 20 mM NH 4NO 3 at pH 5.6, which reduced the build-up of salts on the sampler and skimmer cones. The influences of competing ion (NO 3 −) in the eluent on the retention time and detection sensitivity were investigated to give reasonable resolution and detection limits. Linear plots were obtained in a concentration range of 5.0–500 μg/L and the detection limit was 1.5 μg/L for iodate and 2.0 μg/L for iodide. The proposed method was used to determinate iodate and iodide in seawaters without sample pre-treatment with exception of dilution.

On the feasibility of some photochemical reactions of iodide in seawater

Aerated solutions of potassium iodide in de-ionised water, of between 5–20% (w/v), were exposed to ambient spring sunlight to estimate the rate of photochemical production of molecular iodine from iodide and oxygen in seawater. This rate cannot be measured directly as other reactions, for example the reduction of molecular iodine by organic matter, interfere. Also, a parallel photo-oxidation, initiated by organic matter in real seawater, may also occur. The experiments yield a half-life for iodide in tropical surface waters of about 29 months suggesting that the reaction is insignificant. At this rate it will not compete effectively against the reduction of molecular iodine by organic matter, and hence molecular iodine should not appear. The experiments also consider the photo-oxidation by nitrate, and iodate, a combination of nitrite and oxygen, and eliminate significant interference by chloride, bromide and the phosphate buffer. The rate of photo-oxidation with each of the first three oxidations is found to be first order with respect to oxidant concentration. The variation of photo-oxidation rate with pH is also studied, with a brief investigation without conventional oxidant, where electron cage complexes still promote photo-oxidation. The photochemical action spectrum for these reactions in sunlight is shown to extend between 300 and 425 nm. The photo-oxidation of iodide by iodate is more interesting to marine chemistry as the photo-reduction of iodate. Nevertheless, the reduction-rate is judged to be several orders too low to be significant in seawater. The mechanism of the reactions are discussed and lessons drawn on the stability of potassium iodide solutions used in iodate analysis. The KI actinometer is recommended to those studying other photochemical systems activated by UV-A light as it is linear and very simple and reliable.

Determination of iodide in seawater samples by ion chromatography with chemically-bonded poly(ethylene glycol) stationary phase

An ion chromatographic method for the rapid and direct determination of iodide in seawater is reported. Poly(ethylene glycol) (PEG) groups were chemically bonded onto silica gel or C30-bonded silica gel via diol groups. PEG-bonded C30 binary phases allowed determination of iodide in seawater samples without any interference. Effects of eluent composition on retention behavior of inorganic anions have been investigated. Both cation and anion of the eluent affected the retention of analyte anions. The retention time of anions increased with increasing eluent concentration. The detection limit for iodide obtained by injecting 0.2 μl of sample was 13 μg l −1 (S/N = 3) while the limit of quantitation was 43 μg l −1 (S/N = 10). The present method was successfully applied to the rapid and direct determination of iodide in seawater with long-term durability.

Methyl halide production and loss rates in sea water from field incubation experiments

Experiments were conducted in the field to determine the non-chemical loss rate of methyl iodide in seawater and to examine production rates of methyl halides. The loss rate of added C13 labelled methyl iodide, present at concentrations similar to those found in seawater, corrected for chemical loss due to reaction with Cl − varied from < 1 to 18% day − 1 , with a mean value of 7%. This rate of loss is much lower than that which was proposed by Bell et al. [Bell, N., Hsu, L., Jacob, D. J., Schultz, M. G., Blake, D. R., Butler, J. H., King, D. B., Lobert, J. M., Maier-Reimer, E., 2002. Methyl iodide: Atmospheric budget and use as a tracer of marine convection in global models, Journal of Geophysical Research-Atmospheres 107(D17), 4340-4351.] to account for the large discrepancies between observed and predicted mid-latitude concentrations of CH 3I based on their global photochemical source model. The suitability of several types of container for seawater incubations was studied and only quartz tubes appeared to be free of experimental artifact. Collapsible polyvinyl fluoride containers showed major production of methyl halides on irradiation with simulated sunlight. Polyethylene containers caused spurious production of methyl iodide at lower rates.

Determination of iodide in seawater and edible salt by microcolumn liquid chromatography with poly(ethylene glycol) stationary phase

An ion chromatography method for rapid and direct determination of iodide in seawater and edible salt is reported. Separation was achieved using a laboratory-made C30 packed column ( 100 mm×0.32 mm i.d.) modified with poly(ethylene glycol) (PEG). Effects of eluent composition on retention behavior of inorganic anions have been investigated. Both cation and anion of the eluent affected the retention of analyte anions. The retention time of anions increased with increasing eluent concentration when lithium chloride, sodium chloride, potassium chloride, sodium sulfate, magnesium sulfate were used as the eluent, while it decreased with increasing eluent concentration when ammonium sulfate was used as the eluent. The detection limit for iodide obtained by injecting 0.2 μl of sample was 9 μg/l (S/N = 3). The present method was successfully applied to the rapid and direct determination of iodide in seawater and edible salt samples. Partition may be involved in the present separation mode.