Determination of bromate in bread additives and flours by flow injection analysis

A new, simple, rapid and sensitive spectrophotometric flow injection analysis (FIA) method was developed for the determination of bromate based on its reaction with 3,5-dibromo-PADAP and thiocyanate in a strongly acidic medium. This produced an unstable violet product with a maximum absorption at 602 nm. The calibration curve was linear in the range of 2.00×10⁻⁶–2.10×10⁻⁵ mol/l and the detection limit was 8.00×10⁻⁷ mol/l. The sampling frequency was 90 h⁻¹. The method has been successfully applied to the determination of bromate in commercial bread additives and flours.     

Bromate Formation during Ozonation of Bromide Containing Drinking Water- a Pilot Scale Study

The effect of bromide ion concentration, pH, temperature, alkalinity, and hydrogen peroxide content on bromate formation was studied. Increase in pH was found to give the greatest increase in bromate formation. Also increase in the ozonation temperature, bromide ion concentration and hydrogen peroxide content increased the observed bromate concentration. Only increased alkalinity decreased the bromate formation during the ozonation experiments. Bromate formation exceeded the EU limit value for bromate ion, 10 μg/l, when the initial bromide ion concentration was around 100 μg/l, except for the alkalinity of 1.4 mmol/1, when the bromate formation was 9.4 μg/l.     

Br concentration as an indication of pre-baking bromation of bread products

Br concentration in bread for baked bread products was shown to be linearly proportional to the amount of Br added per kg of flour used to make the product. Br concentration in bread can be used to help identify those bread products with the greatest likelihood of containing bromate residues. Instrumental neutron activation analysis was used to determine Br in test portions of bread products from commercial bakeries, homemade bread, flour, and unbaked dough. High performance liquid chromatography was used to determine the bromate residue in selected test portions.     

Occurrence of bromate, chlorite and chlorate in drinking waters disinfected with hypochlorite reagents. Tracing their origins

Bromate was first reported as a disinfection by-product from ozonated waters, but more recently it has been reported also as a result of treatment using hypochlorite solutions worldwide. The aim of this study was to study the scope of this phenomenon in the drinking waters (n = 509) of Castilla y León, Spain, and in the hypochlorite disinfectant reagents. Two thirds of the treated waters monitored were found to have bromate concentrations higher than 1 µg/l, and of them a median value of 8 µg/l and a maximum of 49 µg/l. These concentrations are higher than those reported so far, however, a great variability can be found. Median values for chlorite were of 5 µg/l, and of 119 µg/l for chlorate. Only 7 out of 40 hypochlorite feedstock solutions were negative for bromate, the rest showing a median of 1022 mg/l; and 4 out of 14 calcium hypochlorite pellets were also negative, the rest with a median of 240 mg/kg. Although bromate is cited as potentially added to water from calcium hypochlorite pellets, no reference is found in scientific literature regarding its real content. Chlorite (median 2646 mg/l) and chlorate (median 20,462 mg/l) and chlorite (median 695 mg/kg) and chlorate (median 9516 mg/kg) were also monitored, respectively, in sodium hypochlorite solutions and calcium hypochlorite pellets. The levels of chlorite and chlorate in water are considered satisfactory, but not those of bromate, undoubtedly owing to the high content of bromide in the raw brines employed by the chlor-alkali manufacturers. Depending on the manufacturer, the bromate concentrations in the treated waters may be very heterogeneous owing to the lack of specification for this contaminant in the disinfectant reagents —the European Norms EN 900 and 901 do not mention it.     

Bromate control in phenol-contaminated water treated by UV and ozone processes

Formation of bromate is of a great concern whenever ozone-based technologies are used for treating highly bromide-containing water ever since bromate was classified as a potential carcinogen. Saudi Arabian groundwater is coincidentally high in bromide content, and the potential of forming bromate during the treatment of such water is high. This study investigated the extent of bromate formation under different treatment conditions of ozone-based Advanced Oxidation Processes (AOPs) when used for the treatment of phenol-contaminated water. The results of the study showed that continuous ozonation at a rate of 1 L/min has completely removed 50 ppm of phenol from contaminated water in less than 5 min. However, as high as 8.85 ppm of bromate (BrO₃⁻) was detected when treating the water which has high concentration of bromide ion (5 ppm). Results also showed that by adjusting the pH to 6 and adding ammonia (NH₃) at a dosage of 1.5 ppm, bromate formation was diminished drastically to non-detected levels.     

四种国标测定氨氮方法述评

作者结合工作经验，评述了测定氨氮的四种国家标准的特点，采用少取水样量稀释之，可以提高测定浓度上限，也解决了氧化剂加量不足或盐度大的问题。因而，对高浓度的样品（0．5—50mg/L）可以用水杨酸法取代纳氏法，避免了后者汞的污染；对低浓度样品（〈0．5mg／L），可以用次溴酸盐法取代苯酚法，克服了后者反应太慢的缺点。QUAATRO连续流动分析仪是可以取代上述方法较好的仪器。     

Effect of Ammonia and Chloramine Pretreatment during the Ozonation of a Colored Groundwater with Elevated Bromide

Ozone coupled with pre-chloramination was evaluated as an effective color removal and bromate control method for groundwater at Mesa Water's Well #8. A modified solution ozone test procedure was employed to simulate the sidestream ozone injection. Satisfactory color removal (<10 PtCo CU) was achieved with 2 mg/L of ozone in the presence or absence of preformed monochloramine or ammonia. While bromate formation was reduced by 67% and 83% with 0.3 and 0.6 mg/L of ammonia-N alone, respectively, 68% and 92% of bromate formation was suppressed with 1.0 and 2.0 mg/L of monochloramine as Cl₂, respectively. Only the pre-treatment with 2.0 mg/L of monochloramine provided sufficient bromate control to meet its maximum contaminant level of 10 μg/L. UV and fluorescence analyses showed effective destruction of color-causing organics by ozone in the presence of preformed monochloramine.     

Micellar sensitized catalytic kinetic spectrophotometry for highly accurate and reproducible determination of Ⅴ(Ⅳ) and Ⅴ(Ⅴ)

A highly accurate and reproducible micellar sensitized kinetic method was proposed for determination of V(VI). The method is based on its catalytic effect on the oxidation of Coomassie brilliant blue R 250(CBB?) by bromate at pH 2.0. The reaction was monitored spectrophotometrically by measuring absorbance change with a fixed-time method of 5 min at 594 and 552 nm with and without surfactant. The variables influencing the calibration sensitivity were extensively investigated, and the optimal conditions were established. The linear calibration range was 10–1,600 lg L-1with a relative SD ranging from 0.35 % to 3.35 %(for five replicate measurements of75, 500, 1,000, and 1,500 lg L-1) and a detection limit of3.8 lg L-1. The selectivity was also investigated, and greatly enhanced by suitable masking agents. The method was successfully applied to the analysis of V(IV) in presence of excess V(V) up to 25 fold in environmental waters with the recoveries of 100.0 %–102.8 % for V(IV) and95.7 %–99.7 % for total V. Its accuracy was validated by analysis of certified reference material via the present kinetic method and standard flame atomic absorption spectrometric method after extractive preconcentration with good agreement between certified and found values.     

Bromate Determination by X-Ray Fluorescence (XRF) to Identify Pre-Baking Potassium Bromate Addition in Bread

Wavelength-dispersive x-ray fluorescence (WDXRF) was applied to determine bromate (Br) as an indication of pre-baking bromate addition in bread. The proposed methodology needed a minimum sample preparation procedure because it was carried out directly on solid samples. The calibration of Br in bread obtained showed low detection limit and high sensitivity to distinguish precisely Br concentrations greater than natural Br. The excellent performance of the present methodology would be useful to identify pre-baking bromation in bread, which can be used to help set up a programme to control bromation in bread. Application of this methodology to bakery control caused an important reduction of bromate use in province of Córdoba, Argentina.     

Dispersion effect of Cs-PW particles on multiwalled carbon nanotubes and their electrocatalytic activity on the reduction of bromate

Hybrid materials based on Cs-PW particles (Cs₃PW₁₂O₄₀) as the polyoxometalate were dispersed in CNTs matrices (multiwalled carbon nanotubes) with different oxidation degree. XRD, SEM, and EDS analyses confirmed the presence of Cs-PW particles in all hybrid materials, and revealed the influence of the CNTs oxidation degree on the dispersion of Cs-PW particles. Hybrids (CNT-S-50 and CNT-S-75) prepared with highly oxidized CNTs (CNT-S) showed the highest dispersion degree of Cs-PW (less segregation) with the best electrochemical behavior. The electrocatalytic properties were evaluated for the first time in the electroreduction of bromate ion, showing interesting results related with the concentration and dispersion degree of the hybrids components.