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PubMed2004

Cyclodextrin-aided determination of iodate and bromate in drinking water by microcolumn ion chromatography with precolumn enrichment.

A selective and simple method for the determination of iodate (IO3-) and bromate (BrO3-) by microcolumn ion chromatography (IC) is presented. In this study, IO3- and BrO3- were determined as IBr2- and tribromide (Br3-), respectively, via a postcolumn reaction with bromide (Br) under acidic conditions with the aid of alpha-cyclodextrin (alpha-CD) in microcolumn IC. IO3- and BrO3- were selectively detected by the present method at a wavelength of 253 or 265 nm. The present system achieved good selectivity for IO3- and BrO3- as well as good repeatability under suitable conditions. Precolumn enrichment improved the detection limit, and allowed the determination of BrO3- in bottled water as low as sub microg L(-1) level in microcolumn IC.

Bromates↗
PubMed2002

[Determination of nitrate and nitrite by catalytic spectrophotometry of potassium bromate-methylene blue system].

Nitrate and nitrite is one of important physical and chemical index in the analysis of environmental samples. A new catalytic spectrophotometric method for the determination of nitrate and nitrite has been established based on the catalytic action of nitrite on the oxidative fading reaction of methylene blue with potassium bromate in dilute phosphoric acid medium. The optimum experimental conditions were investigated in detail, including the selection of measuring wave-length and catalytic reactive medium, the dosage of indicator and oxidizer, the influence of temperature and reactive time, and the interference of co-existent ions with the assay. The results showed that, the linear responses of nitrite and nitrate are in the ranges of 0-200 and 0.003-310 micrograms.L-1 respectively. The method offers the advantages of simplicity, rapidity and sensitivity. It has been applied to analyse water samples with satisfactory results.

Bromates↗
PubMed2004

[Investigation of bromate, haloacetic acids and perchlorate in Beijing's drinking water].

Disinfection by-products and perchlorate in the raw water and finished water of Beijing's a drinking water plants were investigated. The results indicated that there was little bromate in the drinking water. Five haloacetic acids (HAAs) were found in the water. The concentrations of the sum of the five HAAs were ranged from 42.1 micrograms/L to 149.5 micrograms/L. In the HAAs, the chlorine-containing HAAs accounted for more than 90% of the total HAAs. In the five HAAs, the concentration order of the HAAs were trichloroacetic acid > dichloroacetic acid > bromochloroacetic acid > dibromoacetic acid > bromodichloroacetic acid. The HAAs in Beijing's drinking water were much influenced by the variation of season. They had the highest concentrations in September and lowest concentration in April, respectively. For perchlorate in Beijing's drinking water, it was greatly influenced by the groundwater. Its concentrations were between 0.1-6.8 micrograms/L in the finished drinking water. It had peak value in November and minimum value in July, respectively.

Acetates↗
PubMed2004

Removal of bromate and assimilable organic carbon from drinking water using granular activated carbon.

This study investigated the feasibility of using granular activated carbon (GAC) to remove bromate ion (BrO3-) and assimilable organic carbon (AOC) from drinking water through a rapid small-scale column test (RSSCT) method and a pilot-scale study. Results from RSSCT indicated that the GAC capacity for BrO3- removal was dependent on the GAC type, empty bed contact time (EBCT), and source water quality. The GAC with a high number of basic groups and higher pHpzc values showed an increased BrO3- removal capacity. BrO3- removal was improved by increasing EBCT. The high EBCT provides a greater opportunity for BrO3- to be adsorbed and reduced to Br- on the GAC surface. On the other hand, the presence of dissolved organic carbon (DOC) and anions, such as chloride, bromide, and sulfate, resulted in poor BrO3- reduction. In the GAC pilot plant, a GAC column preloaded for 12 months achieved a BrO3- and AOC removal range from 79-96% and 41-75%, respectively. The BrO3- amount removed was found to be proportional to the influent BrO3- concentration. However, the BrO3- removal rate apparently decreased with increasing operation time. In contrast, the AOC apparently increased during the long-term operation period. This may be a result of the contribution due to new GAC being gradually transformed into biological activated carbon (BAC), and the bacterial biomass adsorbed on GAC surface hindering BrO3- reduction by GAC either by blocking pores or adsorbing at the activated sites for BrO3- reduction.

Adsorption↗
PubMed2004

[Catalysis-fluorescence determination of trace nitrite based on the oxidation of acridine orange by potassium bromate].

Acridine orange can be oxidized with discoloring and fluorescence quenching by potassium bromate in phosphoric acid medium, but the reaction rate is very low. The presence of trace nitrite can catalyze this reaction to improve the sensitivity of it apparently and to make the net fluorescence value of the system decrease greatly. Based on the above investigation, a new catalysis-fluorescence determination method of trace nitrite has been proposed. The method described is very sensitive and selective. The catalysis reaction is under the conditions of lambdaex/lambdaem = 446/505 nm, 55 degrees C and 10 min for the reaction time. The method permits the existence of more than 20 common foreign ions. There isn't interference by the same quantity of Fe3+, Br- and I-. The detection limit is 0.012 ng x mL(-1). The linear range of determination is 0.05-5 ng x mL(-1). The method has been used for the determination of trace nitrite in water and soil samples with satisfactory results.

Acridine Orange↗
PubMed2004

[Spectrophotometry determination of trace selenium(IV) in Chinese herbal medicine by catalytic kinetics. I. RDB and potassium bromate].

Trace Se(IV) can catalyze the discolouring oxidizing reaction of RDB with potassium bromate in nitric acid medium, and the conditions of kinetics has been studied in detail. A new method of kinetics spectrophotometry for determination of trace (IV) is established. The sensitivity of the method is 0.905 microg x L(-1). The range of measurement is 0-9.6 microg x L(-1). The method has been used for determining trace Se(IV) in Chinese herbal medicine with satisfactory results.

Bromates↗
PubMed1990

[A case of acute potassium bromate intoxication].

We experienced a case of a 44 year old man who had ingested potassium bromate solution for suicide attempt. Soon after the ingestion, nausea, vomiting, abdominal pain and diarrhea developed in him. Several hours later, he began to complain of auditory disturbance and, in addition, anuric acute renal failure occurred. Direct hemoperfusion and hemodialysis was performed on the patient for the treatment purpose. Five weeks later, he was released from hemodialysis procedure. Gradually, on the other hand, progressing anemia was observed until 90th hospital day, which slowly improved thereafter. Further, pruritus, lower leg pain, headache, tinnitus and loss of sense of taste, etc. were observed in the clinical course. Renal biopsy was performed on the 119th hospital day and the specimen showed the regenerative stage of acute tubular necrosis. In our case, acute renal failure was reversible and, many other clinical manifestations were observed. However slight anemia and irreversible severe auditory disturbance remained unimproved.

Acute Kidney Injury↗
PubMed1986

Dose-response studies on the carcinogenicity of potassium bromate in F344 rats after long-term oral administration.

Dose-response studies on the carcinogenicity of potassium bromate (KBrO3), a food additive, were undertaken to examine its effects at low doses. A total of 148 6-week-old male inbred F344 rats were divided into 7 groups. They were given KBrO3 orally in their drinking water at doses of 500, 250, 125, 60, 30, 15, and 0 ppm for 104 weeks, at the end of which time all the surviving animals were autopsied and then examined histopathologically. Shortening of the survival times and marked inhibition of body weight increase were observed in a group given 500 ppm KBrO3. The combined incidences of renal adenocarcinomas and adenomas were significantly increased in rats treated with KBrO3 at doses of 500, 250, and 125 ppm in a dose-related manner. The dose-response curve showed a sigmoid appearance. The value for the virtually safe dose (VSD), calculated by the probit model, was 0.950 ppm KBrO3 at a risk level of 10(-6). However, significant increases in the occurrence of dysplastic foci of the kidney were found in groups at doses higher than 30 ppm KBrO3. The VSD value for the dysplastic foci estimated by the gamma-multi-hit model was 0.148 X 10(-3) ppm KBrO3 at a risk level of 10(-6). In a group tested with 500 ppm KBrO3, the combined incidences for follicular adenocarcinomas and adenomas of the thyroid and for mesotheliomas of the peritoneum were shown to be significantly increased.

Adenocarcinoma↗
PubMed1985

Dose-related enhancing effect of potassium bromate on renal tumorigenesis in rats initiated with N-ethyl-N-hydroxyethyl-nitrosamine.

Dose-response studies were undertaken to investigate the enhancing activity of potassium bromate (KBrO3), a food additive, on renal tumorigenesis initiated by N-ethyl-N-hydroxyethylnitrosamine (EHEN). A total of 180 male 6-week-old F344 rats were divided into 12 groups. EHEN was given in the drinking water for the first 2 weeks at a concentration of 500 ppm for initiation of carcinogenesis. Thereafter, the rats were treated orally either with KBrO3 at a concentration of 500, 250, 125, 60, 30 or 15 ppm, or with potassium bromide (KBr) at a concentration of 1750 or 350 ppm for 24 weeks. The mean numbers of kidney dysplastic foci were significantly increased in a dose-related manner in rats treated with more than 30 ppm KBrO3. The mean number of renal cell tumors was significantly higher after treatment with KBrO3 at the highest concentration of 500 ppm. On the other hand, KBr had no effect. It was concluded that KBrO3 at doses higher than 30 ppm in the drinking water has an enhancing effect on renal tumorigenesis.

Animals↗
PubMed1994

Toxic mechanism of bromate poisoning in a dog: a case study.

Efforts to link the observed signs in a canine poisoning event with 1 or more possible permanent wave solution chemicals ingested are described. A scenario is presented describing the mechanisms by which the most likely of those compounds, ammonium thioglycolate and sodium or potassium bromate, could have acted to cause both the immediate and delayed signs of acute vestibular dysfunction.

Animals↗
PubMed2005

Stirring-controlled bifurcations in the 1,4-cyclohexanedione-bromate reaction.

We report the experimental observation that stirring in a closed 1,4-cyclohexanedione-bromate reaction can induce transitions not only between oscillatory and nonoscillatory states but also between simple and period-doubled oscillations. Notably, the transition from simple to complex oscillations occurs as a result of increasing stirring rate. When illumination was employed to characterize the importance of microfluctuations of concentrations, the threshold stirring rate for inducing a bifurcation was found to increase proportionally to the intensity of the applied light. Numerical simulations with an existing model illustrate that the experimental phenomena could be qualitatively reproduced by considering effects of mixing on diffusion-limited radical reactions, namely, the disproportion reaction of hydroquinone radicals.

Journal Article↗
PubMed2005

Uncatalyzed reactions in the classical Belousov-Zhabotinsky system. I. Reactions of bromomalonic acid with acidic bromate and with HOBr.

The uncatalyzed reactions of bromomalonic acid (BrMA) with acidic bromate and with hypobromous acid were studied in 1 M sulfuric acid, a usual medium for the oscillatory Belousov-Zhabotinsky (BZ) reaction, by following the rate of the carbon dioxide evolution associated with these reactions. In addition, the decarboxylation rate of dibromomalonic acid (Br2MA) was also measured to determine the first-order rate constant of its decomposition (4.65 x 10(-5) s(-1) in 1 M H2SO4). The dependence of that rate constant on the hydrogen ion concentration suggests a carbocation formation. A slow oligomerization of BrMA observed in sulfuric acid solutions is also rationalized as a carbocationic process. The initial rate of the BrMA-BrO3- reaction is a bilinear function of the BrMA and BrO3- concentrations with a second-order rate constant of 3.8 x 10(-4) M(-1) s(-1). When a great excess of BrO3- is applied, then BrMA is oxidized mostly to CO2. A reaction scheme compatible with the experimental finding is also given. On the other hand, when less BrO3- and more organic substrate - BrMA or malonic acid (MA)--is applied, then addition reactions of various carbocations with the enol form of the organic substrates should be taken into account in later stages of the reaction. It was discovered that HOBr, which brominates BrMA to Br2MA when BrMA is in excess, can also oxidize BrMA when HOBr is in excess. As Br2MA does not react with HOBr, it is assumed that the acyl hypobromite, formed in the first step of the HOBr and BrMA reaction, can react with an additional HOBr to give oxidation products. It was found that the initial rate of the reaction can be described by the following experimental rate law: k(BHOB)[BrMA]0[HOBr]0(2), where k(BHOB) = 5 M(-2) s(-1). A reaction scheme for the oxidation of BrMA by HOBr is given for conditions where HOBr is in excess. Model calculations illustrate qualitatively that the suggested reaction schemes are able to mimic the experiments. (More quantitative simulations are prevented by kinetic data missing for the various carbocation intermediates.) Finally, the effects of these newly observed reactions on oscillatory BZ systems are discussed briefly.

Journal Article↗
PubMed2006

Nuclear magnetic resonance studies of convection in the 1,4-cyclohexanedione-bromate-acid reaction.

The manifestation and development of convection during pattern formation in the 1,4-cyclohexanedione-acid-bromate reaction was investigated using pulsed gradient spin-echo nuclear magnetic resonance (PGSE NMR) experiments. An apparatus was devised that enabled convection to be probed inside an NMR spectrometer and prevented hydrodynamic motion arising from extraneous sources, such as poor mixing or temperature gradients imposed by the experimental setup. PGSE experiments were performed concurrently with magnetic resonance imaging (MRI) experiments to show that convection arose spontaneously from inhomogeneities associated with the chemical patterns. Quantitative data on diffusion coefficients and hydrodynamic velocities are reported.

Journal Article↗
PubMed2006

Measurement of the concentration of Mn2+ and Mn3+ in the manganese-catalyzed 1,4-cyclohexanedione-acid-bromate reaction using redox-triggered magnetic resonance spectroscopy.

A new nuclear magnetic resonance (NMR) experiment is reported, where the spectrometer is triggered using the output from a combination redox electrode. This technique was used to probe redox oscillations in the 1,4-cyclohexanedione-acid-bromate reaction. Manganese(III) acetate or manganese(II) sulfate was used as the catalyst, and the periodic change in concentration of Mn2+/Mn3+ ions was determined as a function of redox potential. The concentration of Mn3+ ions was at a maximum at high redox potential and at a minimum at low redox potential. Also, redox potentials were found to not be dominated by the Mn2+/Mn3+ couple.

Journal Article↗
PubMed2003

Kinetic-catalytic determination of vanadium(IV) using methyl orange-bromate redox reaction.

Determination of V(IV) based on its catalytic effect on the reaction between Methyl Orange and bromate in thepresence of citric acid was studied. The calibration curve obtained by fixed-time method was linear in the range of 2.5-300 ng ml(-1). By use of slope method, a calibration curve containing two linear portions were obtained. Using fixed-time and slope methods, we obtained detection limits of 0.8 and 1.5 ng ml(-1), respectively. Fe2+, As(III), V(V) and Hg2+ interfered. The method was successful for analysis of water samples.

Journal Article↗
PubMed2005

Flow injection determination of formaldehyde by its catalytic effect on the oxidation of sulfonazo III by bromate with spectrophotometric detection.

A simple and sensitive flow injection method with spectrophotometric detection was developed for the determination of formaldehyde. The method is based on the catalytic effect of formaldehyde on the oxidation of sulfonazo III with bromate in acidic media. The decrease in absorbance of the reaction mixture was measured at 566 nm. The calibration graph was linear in the range of 0.005 to 2.80 microg ml(-1) formaldehyde at a rate of 38 +/- 4 samples h(-1). The limit of detection was 4 ng ml(-1). The relative standard deviations for ten replicate measurements of 0.20, 0.50 and 1.00 microg ml(-1) formaldehyde were 1.3, 0.8 and 0.7%, respectively. The method was applied to the determination of formaldehyde in river water, shampoo and melamine-formaldehyde resin.

Journal Article↗
PubMed2001

Tephrosia purpurea ameliorates N-diethylnitrosamine and potassium bromate-mediated renal oxidative stress and toxicity in Wistar rats.

In an earlier communication, we have shown that Tephrosia purpurea ameliorates benzoyl peroxide-induced oxidative stress in murine skin (Saleem et al. 1999). The present study was designed to investigate a chemopreventive efficacy of T purpurea against N-diethylnitrosamine-initiated and potassium bromate-mediated oxidative stress and toxicity in rat kidney. A single intraperitoneal dose of N-diethylnitrosamine (200 mg/kg body weight) one hr prior to the dose of KBrO3 (125 mg/kg body weight) increases microsomal lipid peroxidation and the activity of xanthine oxidase and decreases the activities of renal antioxidant enzymes viz., catalase, glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase, phase II metabolizing enzymes such as glutathione-S-transferase and quinone reductase and causes depletion in the level of renal glutathione content. A sharp increase in blood urea nitrogen and serum creatinine has also been observed. Prophylactic treatment of rats with T. purpurea at doses of 5 mg/kg body weight and 10 mg/kg body weight prevented N-diethylnitrosamine-initiated and KBrO3 promoted renal oxidative stress and toxicity. The susceptibility of renal microsomal membrane for iron ascorbate-induced lipid peroxidation and xanthine oxidase activities were significantly reduced (P<0.01). The depleted levels of glutathione, the inhibited activities of antioxidant enzymes, phase II metabolizing enzymes and the enhanced levels of serum creatinine and blood urea nitrogen were recovered to a significant level (P<0.01). All the antioxidant enzymes were recovered dose-dependently. Our data indicate that T purpurea besides a skin antioxidant can be a potent chemopreventive agent against renal oxidative stress and carcinogenesis induced by N-diethylnitrosamine and KBrO3.

Animals↗