Bromide Ion Concentration Research Articles

A simple determination method of bromide ion in plasma of methyl bromide workers by head space gas chromatography

An improved method for the simple determination of bromide ion in plasma is described. It was modified from the method by Kawai, Sugiyama et al. (1985). In the improved method, 200 microliters of plasma and 800 microliters of distilled water were placed in a reaction vial to which 100 microliters of dimethyl sulfate was added. The reaction vial was immediately sealed, placed in an incubator at 85 degrees C, and shaken for 10 min. At the end of the reaction, a gas-tight syringe was used to draw out the head space gas of 1 ml. The methyl bromide gas was then injected into a gas chromatograph and methyl bromide was determined with F.I.D. A good linear relationship was obtained between the peak area of methyl bromide and the concentration of bromide ion within the range of 0.5 to 500 ppm. Bromide ion in the range of 0.5 to 500 ppm in standard solution was added to the plasma samples. After 10 repeated measurements, the relative standard deviation was found to be in the range of 2.8-3.6% and recovery was over 96%. The analytical results of this method were compared with those obtained by spectrophotometry. The analytical results obtained by the two methods were in good agreement (r = 0.9669) in plasma samples of 10 methyl bromide workers. A study to determine bromide ion concentration in 39 methyl bromide workers was made and the results were compared with those observed in 100 workers (control group) not exposed to methyl bromide.(ABSTRACT TRUNCATED AT 250 WORDS)

Residues after fumigation with methyl bromide: Bromide ion and methyl bromide in middlings and final cereal foodstuffs

Methyl bromide and bromide ion concentrations were estimated in pasta manufactured before and after fumigation with methyl bromide. The first trial estimated the bromide ion concentrations in fumigated and unfumigated flours and in pastas obtained from these. The concentration of bromide ions in fumigated flours was not significantly different from unfumigated flours. Only some pastas, manufactured from fumigated flours, showed a higher bromide ion concentration than those manufactured from unfumigated flours. The second trial evaluated the bromide ion concentrations of rices, white flours, flours, pastas made only from flours, pastas with eggs and pastas with eggs and spinach, before and after exposure to methyl bromide in their retail packagings. The bromide ion concentrations in fumigated pastas with eggs, pastas with eggs and spinach and rice were higher than in those unfumigated. In the pastas with eggs the bromide ion concentration after fumigation increased ten times (from about 4 to 40 mg/kg). Results showed that the bromide ion and methyl bromide levels estimated in all the foodstuffs examined were lower than the maximum limits fixed by several different national regulations.

Enzymatic formation of propylene bromohydrin from propylene by glucose oxidase and lactoperoxidase

The time course of the peroxidative bromination of propylene accompanied by in situ generation of hydrogen peroxide by glucose oxidase was examined to improve the productivity of propylene bromohydrin. To prevent the rapid inactivation of lactoperoxidase by excess hydrogen peroxide, it was effective to use lactoperoxidase in large excess as compared with glucose oxidase, and to raise the concentration of bromide ion. However, the rate of glucose consumption was lowered at high concentrations of bromide ion, and at higher mole fraction of oxygen as compared with propylene in the gas mixture. Therefore, it seemed that for the favorable production of bromohydrin there existed the optimal conditions for the concentration of bromide ion and for the composition of oxygen-propylene gas mixture. Such kinetic behaviors of the sequential enzymatic reactions were explained by a mechanism involving free hypobromous acid as a reactive intermediate. Furthermore, the stability of the coimmobilized enzymes with k-carrageenan gels was investigated in continuous operations. The half-life of the enzymes was ca. 60 h for the production of propylene bromohydrin.

Stability of Aggregates in Aqueous Solution of Dialkyldimethylammonium Bromides

The concentration of bromide ion was measured by an ion electrode method and a titration for the stirred and sonicated aqueous solution of didodecyl-, ditetradecyl-, and dihexadecyl-dimethylammonium bromides. The observed bromide concentration, combined with the surface tension and the molar conductivity, was correlated to the forms of the aggregates in the solution. And the stability of the aggregates was also estimated.

Subacute inhalation experiment for methyl bromide in rats.

Male rats were exposed to four different concentrations of methyl bromide for 4 hrs/day ; 150 ppm for 11 weeks, 55 times, and to 200, 300, and 400 ppm for 6 weeks, 30 times. Changes in body weight, general condition and hema-tology, changes in organ weight, residual bromide ion concentration, and histopa-thology of several organs were studied. Suppression of body weight increment, abnormal clinical signs and severe weakness were found in the highly exposed group. Bromide ion accumulation was seen especially in the kidney and spleen, without significant dose-related change.Remarkable changes appeared histopathologically in the brain and heart. Necrosis was exhibited zonally from the first to fourth layers of the dorso-external cortex bilaterally, showing a spongy, edematous and hyperemic appearance, accompanied by proliferation of blood vessels. This bilateral lesion had spread selectively to basal nuclei and brain stem. Multiple, small focal necroses were found in wide regions of the heart. Necrosis of the brain and heart, both of which have high sensitivity to oxygen defficiency, was thought to be caused by the longterm hypoxic condition as manifested in the histopathological findings.

Bromoform Formation in Ozonated Groundwater Containing Bromide and Humic Substances

The effect of bromide ion, organic carbon concentration (natural aquatic humic substances), pH, and solar irradiation on the formation of bromoform in ozonated groundwater has been studied. The studies were conducted on four unique samples of groundwater taken from different regions of the Biscayne Aquifer in southern Florida. All other conditions being equal, increases in bromide ion concentrations resulted in increases in CHBrg formation. In three of the four samples, CHBr3 formation decreased as the pH level increased from 5 to 9. The fourth sample exhibited an opposite trend whereby the CHBr3 concentration increased with increasing pH. Bromoform concentration increased with increased O3 concentration over an ozone dosage range of 3.4 to 6.7 mg/L.

Utilisation de l'electrochimie dans la transformation des produits issus de la biomasse oxydation anodique indirecte de l'isosorbide

The electrochemical method is used to carry out the anodic oxidation of isosorbide-4,8-dihydroxy-2,6-dioxabicyclo[3.3.0]octane[1R,4S,5R,8R] into 4-hydroxy-2,6-dioxabicyclo[3.3.0]octan-8-one. The reaction conditions have been optimized and maximum conversion yields were obtained under conditions of mixed electrolysis conducted in the presence of sodium bromide in water and a platinum anode. The transformation mechanism and the nature of the oxidant transient are discussed in relation to conventional parameters: pH, current density, bromide ion concentration, temperature, etc.

Kinetic investigation of the oxidation of bromide ions by cobalt(III). Part 1.—The influence of pyridine in acetic acid solvent

A kinetic investigation of the reduction of cobalt(III) acetate by bromide ions in acetic acid and in the presence of pyridine at 60–93 °C has shown that the initial rate obeys the rate law –(d[CoIII]//dt)0=–(d[Br–]//dt)0=kobs[CoIII]2[HBr]2//[CoII][Py]2. A mechanism is proposed involving the formation of bromine anion radicals as intermediates. Pyridine or other amines influence mainly (i) the actual concentration of bromide ions, (ii) the dissociation of active dimeric CoIII species and (iii) the exchange of bromide ligands.

Quasi-elastic neutron scattering measurements of molecular motions in micelles and microemulsions

Quasi-elastic incoherent neutron scattering has been used to study the dynamics of individual molecular components in different micellar and microemulsion aggregates. The transition from a micelle to a microemulsion was achieved by adding alcohol to normal micelles, forming mixed surfactant/alcohol micelles and then adding oil, producing an oil-in-water microemulsion. The proportions of oil and water were then reversed, thus making a water-in-oil microemulsion. IN all cases fast lateral motion of the surfactant around the aggregate surface is observed. The rate of motion is independent of the aggregate size and structure and of the amount of alcohol. The diffusion constant of the alcohol suggests that it is intercalated between the surfactant chains. The oil core of the oil-in-water microemulsion has a diffusion constant comparable to the bulk liquid hydrocarbon, whereas that of the water core of the water-in-oil microemulsions is less than that of bulk water. This difference presumably arises from the high concentration of bromide ions in the water core.

Extraction-fluorimetric determination of mercury with 2-phenylbenzo[8,9]quinolizino[4,5,6,7-fed]phenanthridinylium perchlorate

The characteristics of 2-phenylbenzo[8,9]quinolizino[4,5,6,7-fed] phenanthridinylium perchlorate (PQPP) as a reagent for the formation of ion-association complexes with metal-bromide anions and its application to the fluorimetric determination of mercury are described. This reagent forms a 1: 1 complex with HgBr3-that is slightly soluble in water and can be extracted with butyl acetate. The influence of the acidity, bromide ion concentration and foreign ions were investigated. Mercury can be determined in the range 1.5–15 ng ml–1. The stoicheiometry and apparent stability constant of the complex were determined. The method is applicable to the determination of mercury in sphalerites and organomercurials in cleaning solutions for contact lenses.

Bromide ion concentration and Br/Cl ratio of ground water in the southwest region of Gifu Prefecture

Bromide ion concentration and Br/Cl ratio of ground water in the southwest region of Gifu Prefecture

Bromide-ion balance of a polder district with large-scale use of methyl bromide for soil fumigation

When concentrations of bromide ion were determined in waters in a polder district of The Netherlands where there is large-scale use of methyl bromide for soil fumigation, the maximum concentrations in precipitation, surface water and ground water were found to be 0.98, 41 and 17 g/m 3, respectively. The highest concentrations of bromide ion in surface water were found in September–October during the main fumigation season. For the period 1 September 1979 to 31 August 1980 a bromide-ion balance was computed for the polder district. The contribution of the use of methyl bromide to the input of bromide ion in the polder district was 215 Mg (Mg = 1000 kg), which corresponds to 68% of the total input of bromide ion (318 Mg). On average over a year, about 14% of the dosage of methyl bromide applied for soil fumigation was converted to bromide ion.

Uncatalysed oscillations in the bromate — pyrogallol system

Studies on the bromate-pyrogallol system with sulphuric and perchloric acids are presented. The addition of acrylamide and acrylonitrile to the oscillatory system indicates the presence of free radicals. The apparent energy of activation for the overall process is 10.1± 1 and 20 ± 0.5 kcal mol-1 respectively for sulphuric and perchloric acids. The static potential measurements with different constituents together with double recording of oscillations with a platinum and Ag/AgBr indicator electrode establish that oscillations are caused by continuous change in the concentration of bromine and bromide ions.

ChemInform Abstract: THE KINETICS OF SILVER BROMIDE FILM FORMATION ON THE SILVER ANODE

AbstractDie anodische potentiodynamische Bildung von AgBr‐Filmen auf einer rotierenden Ag‐Elektrode (rde) wurde in wäßrigen Bf‐Lösungen untersucht.

Dynamics of Bromide Uptake and Depuration by Fathead Minnows

Abstract The uptake and depuration of bromide ion by fathead minnows Pimephales promelas were studied in flowing water with bromide ion concentrations of 0, 39.8, and 386 mg/liter. The rate constant for the uptake of bromide by fish decreased from 1.999 day-1 at the lower exposure concentration (39.8 mg/liter) to 0.588 day-1 at the higher concentration (386 mg/liter). The equilibrium bioconcentration factor (ratio of bromide concentration in the fish to that in water) varied with the bromide concentration in water: 6.7 and 37 at the lower and higher concentrations, respectively. At equilibrium, the ratio of bromide to total halides in the fish was equal to that in the water. Depuration rates, 0.054–0.087 day-1, were independent of initial bromide concentrations. The amount of bromide accumulated in the fish appears to be limited by the amount of total halide occurring naturally in the fish. Fathead minnows apparently are unable to distinguish between bromide and chloride ions. Therefore, the whole-body io...

The kinetics of silver bromide film formation on the silver anode

The anodic potentiodynamic formation of an AgBr film on an Ag rotating disc electrode was studied in aqueous bromide solutions. As the electron transfer step (1) is intrinsically fast, ▪ and as the film remains porous throughout its growth, the rate of film growth is limited by physical parameters such as ionic diffusion and migration in the solution. The anodic E/ I curves for AgBr film formation were calculated quantitatively by computer on the basis of the following model of film growth. Film formation occurs initially by the nucleation of islands of film to a critical thickness, and then these islands spread laterally until only small pores remain between them. As these pores become small, the resistance of the solution within them becomes rate limiting (at the anodic current peak). After the peak, the concentration of bromide ions at the pore base falls to zero and current is then controlled by the diffusion of bromide ions into the lengthening pores of the film. This lateral spreading mechanism and the subsequent retention of the porous film morphology has been substantiated by comprehensive Scanning Electron Microscope investigations.

The nature of pb(II)-bromide complexes in propylene carbonate

The greatly increased solubility of PbBr 2 in propylene carbonate (PC) caused by addition of LiBr indicates that PB(II) interacts strongly with bromide ion in propylene carbonate to form stable Pb(II)-bromide complexes. Solubility and spectrophotometric data for LiBr solutions saturated with PbBr 2 indicate the presence of two Pb(II)-bromide complexes whose bromide:lead ratios are respectively 3.00 and 2.75. The former, which predominates in dilute (<0.03 m) solutions of LiBr saturated with PbBr 2 , was shown by potentiometry and solubility data to be PbBr 3 − , a species also formed when PbBr 2 dissolves in PC in the absence of LiBr. The latter, which is predominant in more concentrated LiBr solutions saturated wih PbBr 2 , was shown by spectrophotometry and solubility data to be the polynuclear complex Pb 4 Br 11 −3 . Both complexes are sufficiently stable that the free bromide ion concentration in these solutions corresponds to only a small fraction of the total bromide concentration. In LiBr solutions unsaturated with respect to PbBr 2 , the major Pb(II) species are PbBr 3 − and PbBr 4 −2 .

The kinetics and mechanism of thioamide hydrolysis promoted by gold(III) bromides in aqueous solution

Kinetic and spectroscopic studies are reported of the reactions of N-cyclohexylthiobenzamide with the ions AuBr4– and trans-Au(CN)2Br2– in aqueous solutions to give the corresponding O-benzamide. The effects of temperature, pH, ionic strength, and ambient bromide ion concentration are described and mechanisms for the reactions suggested. The reactions involve the rapid, stoicheiometric formation of S-amide–gold(III) ion adducts which decompose slowly to the O-amide. Comparison of the results with those of previous studies shows that, for square planar adducts, the rate of the desulphurisation process is increased by an increase in (i) the positive charge on the gold atom and (ii) the softness of the attached ligands. In the presence of added ambient bromide ions the gold ions and adducts are partially or completely converted into octahedral species. The desulphurisation process in the octahedral adducts is faster than in the square planar adducts.

Kinetic investigation of the bromate–ascorbic acid–malonic acid system

AbstractAccording to our experiments the bromide ion concentration exhibits in the bromate–ascorbic acid–malonic acid–perchloric acid system three extrema as a function of time. To describe this peculiar phenomenon, the kinetics of four component reactions have been studied separately. The following rate equations were obtained:Bromate–ascorbic acid reaction: Bromate–bromide ion reaction: Bromide–ascorbic acid reaction: Bromine–malonic acid reaction: k4 = 6 × 10−3 s−1, k‐4 ≥ 1.7 × 103 s−1, k5 ≥ 1 × 107M−1 · s−1Taking into account the stoichiometry of the component reactions and using these rate equations, the concentration versus time curves of the composite system were calculated. Although the agreement is not as good as in the case of the component reactions, it is remarkable that this kinetic structure exhibits the three extrema found.

The asymptotic behavior of solutions of a system of reaction-diffusion equations which models the Belousov-Zhabotinskii chemical reaction

We investigate the boundary value problem ∂u ∂t = ∂ 2u ∂x 2 + u(1 − u − rv) , ∂v ∂t = ∂ 2v ∂x 2 − buv , u(−∞, t) = v(∞, t) = 0, u(∞, t) = 1, and v(−∞, t) = γ ∀ t > 0 where r > 0, b > 0, γ > 0 and x ϵ R. This system has been proposed by Murray as a model for the propagation of wave fronts of chemical activity in the Belousov-Zhabotinskii chemical reaction. Here u and v are proportional to the concentrations of bromous acid and bromide ion, respectively. We determine the global stability of the constant solution ( u, v) ≡ (1,0). Furthermore we introduce a moving coordinate and for each fixed x ϵ R we investigate the asymptotic behavior of u( x + ct, t) and v( x + ct, t) as t → ∞ for both large and small values of the wave speed c ⩾ 0.