Acoustic properties of incompletely miscible alkali fluoride and bromide melts

Ultrasound velocities were measured in exsolving ionic melts of lithium fluoride doped with potassium, rubidium, and cesium bromides. The role of dimensional and temperature factors in the exsolution of systems in which Coulombic particle interactions dominate is discussed. Original Russian Text ? V.I. Minchenko, V.P. Stepanov, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol. 83, No. 1, pp. 147–151.     

Stripping voltammetry of bromide and iodide ions at a renewal silver electrode

The behavior of bromide and iodide ions at a silver electrode renewed by cutting off a thin 0.5-μm surface layer was studied. The advantage of this method of electrode renewal over some variants of mechanical renewal was demonstrated. It was shown that bromide and iodide ions can be determined in concentration ranges from 10^-6 to 10^-3 M and from 10^-7 to 10^-3 M, respectively. Deceased.     

The vitrification of alkali borate and alkali silicate melts

Glasses and crystals of compositions corresponding to the congruently melting compounds M₂O·2SiO₂ (M = Na. Rb, and Cs) and M₂O·4SiO₂ (M = K, Rb, and Cs) were studied by differential scanning calorimetry. The structure temperatures (T _f) and excess entropies at T _f of glasses were measured depending on the rate of cooling of the corresponding melts. The activation energies of glass formation (ΔE) and scale of cooperative motion in the transition region (ξ_a) were estimated. The totality of the data obtained were used to compare the thermodynamic (the ratio between the excess (with respect to the corresponding crystals) entropy of glass at T _f and the entropy of crystal melting), kinetic (fragility m = f(ΔE, T _f)), and microscopic (ξ_a) parameters of the vitrification of alkali silicate melts. The behaviors of alkali silicate and alkali borate melts were shown to be similar.     

Electrochemistry of iodine and iodide in chloroaluminate melts

The electrochemical behavior of iodine and iodide has been studied in AlCl₃+NaCl mixtures with compositions ranging from NaCl saturated melts to AlCl₃+NaCl (63+37 mol %) at platinum and tungsten electrodes. Iodide is oxidized in two steps to iodine and I(I); a reduction wave to iodide and an oxidation wave to I(I) are obtained in iodine solutions. The equilibrium constant for the reaction, I^?+I(I)=I₂, is 6×10⁸ l mol^?1 in molten chloroaluminate melts at 175°C.     

Determination of iodide and bromide by flow methods with amperometric detection

Determination of bromide and iodide in real samples (water, pharmaceutical preparations, and biological material) was performed using modified flow injection analyses (FIA) with amperometric detection on platinum electrode. As an additional confirmation of FIA experiments, cyclic voltammetry was employed. Iodide was determined by the kinetic method, its limit of detection was 1.0 nM, and the linearity was 0.1–100 μM. The limit of detection for bromide determination was 50.0 nM and the calibration was linear for 2.5–100 μM and 0.1–10 mM. The relative standard deviation for 1 μM of iodide was 3.03% and, for 5 μM of bromide, it was 1.23% (n = 6). Both methods enable 60 analyses per hour to be performed. The text was submitted by the authors in English.     

Flow-injection determination of iodide with a silver electrode

A procedure is developed for the flow-injection determination of iodide using a modified silver electrode; it extends the analytical range of iodide by an order of magnitude as compared to potentiometric determination using an iodide-selective electrode with a polycrystalline membrane. The detection limit is 7 μg/L. The procedure was used to determine iodide in natural mineral waters and model solutions. The throughput was 20–25 samples/h.     

Determination of iodide and bromide by ion chromatography with post-column reaction detection

During an investigation into the mechanism of the biosynthesis of thyroid hormones, it became necessary to determine traces of iodide and bromide in biological matrices as well as in food. A vydac 302-IC anion-exchange column with methanesulphonic acid as the mobile phase was used for the ion chromatographic separation of iodide and bromide. A post-column reaction detector was developed based on the reaction between iodide or bromide, chloramine-T and 4,4'-bis(dimethylamino)diphenylmethane. Methods with minimal sample preparation are described for determination of iodide or bromide in serum, milk, salt and water. The detection limit is ca. 20 pg iodide and 15 ng bromide injected.     

Selective determination of bromide and iodide in serum and urine by gas chromatography

A gas chromatographie method with electron capture detection is described for the simultaneous determination of bromide and iodide in biological matrices such as serum and urine. Samples are purified by passing them through a disposable C-18 reversed phase silica cartridge; bromide and iodide are derivatized in acid medium to 2-bromoethanol and 2-iodoethanol by ethylene oxide and the derivatives are extraced into ethyl acetate. Detection limits are in the low ng/ml-range.     

Preparation of an iodide ion-selective electrode by chemical treatment of a silver wire

The preparation and application of an iodide ion-selective electrode, prepared by chemical treatment of a silver wire with Hg(2+) is described. The electrode is suitable for the direct potentiometric measurement of iodide in aqueous solutions with concentrations down to 1 x 10(-6) mol/L. It can be used for potentiometric measurements of various compounds (vitamin C, glutathione).     

Preparation of an iodide ion-selective electrode by chemical treatment of a silver wire

The preparation and application of an iodide ion-selective electrode, prepared by chemical treatment of a silver wire with Hg²⁺ is described. The electrode is suitable for the direct potentiometric measurement of iodide in aqueous solutions with concentrations down to 1 × 10^–6 mol/L. It can be used for potentiometric measurements of various compounds (vitamin C, glutathione).     

Specific adsorption of bromide and iodide ions from N-methyl formamide solutions with constant ionic strength on liquid ga electrode

The differential capacitance curves were measured with an ac bridge in the Ga/[N-MF + 0.1 m M KBr + 0.1 (1 − m) M KClO₄] and Ga/[N-MF + 0.1 m M KI + 0.1 (1 − m) M KClO₄] systems at the following fractions m of surface-active anions: 0, 0.01, 0.02, 0.05, 0.1, 0.2, 0.5, and 1. As compared with other solvents, N-methyl formamide (N-MF) enables one to realize the largest positive charges of Ga electrode, at which it remains ideally polarizable (up to 20 μ/cm²). The data on the specific adsorption of Br⁻ and I⁻ anions in the system can be quantitatively described by the Frumkin’s isotherm; to the first approximation, free energy of halide ion (Hal⁻) adsorption DG_{adsHal ^{- 1}} \Delta G_{adsHal^{ - 1} } is a linear function of electrode charge. It is found that, in contrast to the Hg/N-MF interface, DG_{adsHal ^{- 1}} \Delta G_{adsHal^{ - 1} } at the Ga/N-MF interface varies in the reverse order: Br^t— ∼ I⁻ < Cl⁻. From the measured results, we can conclude that the energy of metal-Hal⁻ interaction increases in series: $\Delta G_{M - Cl^ - } > \Delta G_{M - Br^ - } > \Delta G_{M - I^ - } $\Delta G_{M - Cl^ - } > \Delta G_{M - Br^ - } > \Delta G_{M - I^ - } and the difference (DG_{Ga - Hal1^-} - DG_{Ga - Hal2^-} )(\Delta G_{Ga - Hal_1^ - } - \Delta G_{Ga - Hal_2^ - } ) is larger than the difference between the solvation energies of Hal^- (DG_{S - Hal1^-} - DG_{S - Hal2^-} )Hal^ - (\Delta G_{S - Hal_1^ - } - \Delta G_{S - Hal_2^ - } ).     

Physicochemical studies of the cetyltrimethylammonium bromide micellar system using a bromide selective electrode

The use of the bromide selective electrode in physicochemical studies of the cationic micellar system of cetyltrimethylammonium bromide (CTAB) is described. Potentiometric methods and appropriate equations have been developed and used to determine the critical micellar concentration, the ionization degree, and the apparent ion-exchange constants of various anions (fluoride, chloride, hydroxide, acetate, nitrate, sulfate and borate). The interaction of the cationic micelles of CTAB with various species [the lipophilic reagent 1-fluoro-2,4-dinitrobenzene, the anionic succinate and the cationic tris-(hydroxymethyl)-aminomethane] was monitored through the measurement of the changes in the concentration of the free bromide counterions.     

Spectrophotometric determination of bromide (and iodide) in a flow system after oxidation by peroxodisulphate

The peroxodisulphate method for the determination of bromide has been modified. A flow-injection system for the spectrophotometric finish has been developed and the size of the ion-exchange column in the preconcentration step has been scaled down. The sum of bromate and iodate produced in the oxidation is determined by treating the oxidized sample with iodide in hydrochloric acid. The iodate is separately determined by applying the reaction in acetic acid. The working range of the spectrophotometric finish is 1-15muM and the limit of determination (10 sigma) is 0.7muM for iodate and for iodate plus bromate. The enrichment factor in the preconcentration step is 50, yielding a limit of determination of 15nM for bromide in natural waters. Eighteen samples of water from the Baltic, with salinity ranging from 3 to 33%. have been analysed. A Br/Cl ratio of (1.53 +/- 0.02) x 10(-3) was found. A comparative study of the original and the new preconcentration step has been made with three river waters, rich in humic substances. The results agreed within +/- 1. 5%.     

利用碘离子增感效应和金电极导数阳极溶出法研究铜丶铅和镉的同时测定

A method of simultaneous determination of copper (II), lead (II) and cadmium (II) in sulphuric acid-iocide ion medium was established by derivative anodic stripping voltammetry (DASV) on the gold electrode. The peak theights of lead and cadmium were increased by enhancement effect of iodide ion and the peaks of bismuth and copper were well formed and completely resolved on gold electrode in the presence of iodide ion, therefore peak of copper is not affected by bismuth. The sensitivities for copper, lead and cadmium were very high and their peak potentials in the stripping voltammogram were +0.25, -0.2 and -0.27 volt, respectively. The dependence of peak height of these elemets on their concentrations was linear. The detection limits for copper, lead and cadmium were 0.2 0.2 and 0.05 ppb, respectively. We have further studied the electrode process by means of triangle cyclic voltammetry and proved that he electrode reaction of copper is reversible, and that the reversibility of electrode reactions of lead and cadmium is not good.     

Determination of cadmium(II) at a gold electrode in the presence of selenium(IV) by anodic-stripping voltammetry with enhancement by iodide ion

Anodic-stripping voltammetry (ASV) has been used in the derivative mode for the determination of cadmium, with a gold electrode in sulphuric add medium containing seleniurn(IV). The peak height for cadmium is enhanced by the presence of iodide. The sensitivity for cadmium is very high, with a peak in the stripping voltamperogram at -0.27V (vs. Ag/AgCl). The peak height for cadmium is not affected by over a 100-fold level of lead in the presence of selenium(IV). The dependence of peak height on the cadmium concentration is linear in the range 0.05-10ng ml .     

Determination of iodide and bromide by chemiluminescence methods coupled with dynamic gas extraction

Summary Hybrid methods for the determination of bromide and iodide have been developed, based on the selective oxidation of halides, dynamic gas extraction of the corresponding halogens and their chemiluminescent detection by luminol. The limit of determination for bromides is 0.0013 mg/l, for iodides 0.003 mg/l; time required for analysis is 1–2 min. The methods have been applied to the analysis of natural waters.

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Bestimmung von Iodid und Bromid mit Hilfe der Chemiluminescenz in Verbindung mit dynamischer Gasextraktion