Bromates detection

The results obtained for the vast majority of the laboratories carrying out the ISO 15061 IC method were considered to be fit for the purpose. In addition to this method, five alternative methods suitable for trace bromate determinations were also considered, namely on-line IC-ICP-MS, simple on-line column chromatography ICP-MS, IC with chlorpromazine post-column reaction and colorimetric detection, and fluorescence quenching with Carbostyril (with pre-treatment), which are all capable of achieving a bromate detection limit below 1 xg/L. A field method with methylene blue and fluorescence quenching with Carbostyril without sample pretreatment did not lead to satisfactory results at this level of bromate concentrations. 

Known today as EPA Method 302.0 [73], this method can be fully automated using a dual-channel reagent-free IC (RFIC ) system. Bromate detection limits equivalent to or better than postcolumn derivatization methods can be... 

The pH must be kept at 7.0—7.2 for this method to be quantitative and to give a stable end poiut. This condition is easily met by addition of soHd sodium bicarbonate to neutralize the HI formed. With starch as iudicator and an appropriate standardized iodine solution, this method is appHcable to both concentrated and dilute (to ca 50 ppm) hydraziue solutious. The iodiue solutiou is best standardized usiug mouohydraziuium sulfate or sodium thiosulfate. Using an iodide-selective electrode, low levels down to the ppb range are detectable (see Electro analytical techniques) (141,142). Potassium iodate (143,144), bromate (145), and permanganate (146) have also been employed as oxidants. 

Chloramine-T (A -chloro-p-toluenesulfonamide sodium salt) 3H2O [7080-50-4] M 281.7, m 168-170°(dec). Crystd from hot water (2mL/g). Dried in a desiccator over CaCh where it loses water. Protect from sunlight. Used for detection of bromate and halogens, and Co, Cr, Fe, Hg, Mn, Ni and Sb ions. 

The presence of free bromine, and consequently the end-point, can be detected by its yellow colour, but it is better to use indicators such as methyl orange, methyl red, naphthalene black 12B, xylidine ponceau, and fuchsine. These indicators have their usual colour in acid solution, but are destroyed by the first excess of bromine. With all irreversible oxidation indicators the destruction of the indicator is often premature to a slight extent a little additional indicator is usually required near the end point. The quantity of bromate solution consumed by the indicator is exceedingly small, and the blank can be neglected for 0.02M solutions. Direct titrations with bromate solution in the presence of irreversible dyestuff indicators are usually made in hydrochloric acid solution, the concentration of which should be at least 1.5-2M. At the end of the titration some chlorine may appear by virtue of the reaction ... 

The titrations should be carried out slowly so that the indicator change, which is a time reaction, may be readily detected. If the determinations are to be executed rapidly, the volume of the bromate solution to be used must be known approximately, since ordinarily with irreversible dyestuff indicators there is no simple way of ascertaining when the end point is close at hand. With the highly coloured indicators (xylidine ponceau, fuchsine, or naphthalene black 12B), the colour fades as the end point is approached (owing to local excess of bromate) and another drop of indicator can be added. At the end point the indicator is irreversibly destroyed and the solution becomes colourless or almost so. If the fading of the indicator is confused with the equivalence point, another drop of the indicator may be added. If the indicator has faded, the additional drop will colour the solution if the end point has been reached, the additional drop of indicator will be destroyed by the slight excess of bromate present in the solution. 

Another interesting TLC method for the isolation and determination of bromate ion in flour dough and breads has been developed [59]. It involves extraction of BrOj from foodstuff, purification on alumina column, TLC separation on silica gel layer developed with water -1- -butanol + n-propanol (1 1 3), and quantification by densitometry. Bromate ion down to 0.1 pg in bread (1.0 g) was detected with tohdin-FIQ reagent. 

Separation and detection methods Ion chromatography is routinely used for the isolation of bromate. Diverse detection methods are mentioned in the literature, including isotope dilution analysis (Creed and Brockhoff 1999), conductivity measurement (Jackson et al. 1998), fluorimetric determination (Gahr et al. 1998), ICP-MS (Seubert and Nowak 1998) and spectrophotometry (Achilii and Romele 1999),... 

Creed JT, and Brockhoff CA (1999) Isotope dilution analysis of bromate in drinking water matrixes by ion chromatography with inductively coupled plasma mass spectrometric detection. Anal Chem 71 722-726. 

Figure 3 Gradient separation of anions using suppressed conductivity detection. Column 0.4 x 15 cm AS5A, 5 p latex-coated resin (Dionex). Eluent 750 pM NaOH, 0-5 min., then to 85 mM NaOH in 30 min. Flow 1 ml/min. 1 fluoride, 2 a-hydrox-ybutyrate, 3 acetate, 4 glycolate, 5 butyrate, 6 gluconate, 7 a-hydroxyvalerate, 8 formate, 9 valerate, 10 pyruvate, 11 monochloroacetate, 12 bromate, 13 chloride, 14 galacturonate, 15 nitrite, 16 glucuronate, 17 dichloroacetate, 18 trifluoroacetate, 19 phosphite, 20 selenite, 21 bromide, 22 nitrate, 23 sulfate, 24 oxalate, 25 selenate, 26 a-ketoglutarate, 27 fumarate, 28 phthalate, 29 oxalacetate, 30 phosphate, 31 arsenate, 32 chromate, 33 citrate, 34 isocitrate, 35 ds-aconitate, 36 trans-aconitate. (Reproduced with permission of Elsevier Science from Rocklin, R. D., Pohl, C. A., and Schibler, J. A., /. Chromatogr., 411, 107, 1987.)...

Shi and Adams recently created a rapid IC/ICF-MS method for simultaneously measuring iodoacetic acids, bromoacetic acids, iodate, and bromate in drinking water, groundwater, surface water, and swimming pool water [165]. Method detection limits were sub-pg/L for iodinated DBFs, and low-pg/L for brominated DBFs. 

Bromate has also been measured using 1C with conductivity detection. For example, EPA Method 302.0 uses two-dimensional 1C with suppressed conductivity detection to measure bromate at 0.12 pg/L detection limits [166]. Bromate, chlorite, and chlorate can also be measured by an earlier EPA Method (Method 300.1), which uses 1C with conductivity detection [167]. Method detection limits ranging from 0.45 to 1.28 pg/L can be achieved. 

Wagner P, Pepich BV, Pohl C, Srinivasan K, De Borba B, Lin R, Munch DJ (2009) EPA Method 302.0. Determination of bromate in drinking water using two-dimensional ion chromatography with suppressed conductivity detection. U.S. EPA, Cincinnati, OH, Available at http //water.epa.gOv/scitech/drinkingwaterAabcert/upload/met302 0.pdf... 

Table 6 presents a summary of toxic and classical pollutants detected in three common cleansing solutions ammoniacal sodium bromate, hydrochloric acid without copper complexer, and hydrochloric acid with copper complexer. 

Bromine (from the Greek bromos for stench ) has found applications in flue gas desulfurization [106], in the design for a large-scale electrical power storage facility [107], in many flame retardants, for fire extinguishers, and in pharmaceuticals. Electrobromination processes have been employed directly and indirectly, and bromates are produced [108] and detected [109] electrochemically. Perbro-mates when compared to perchlorates and periodates are chemically very unstable. A summary of redox states, standard potentials in acidic aqueous media, and typical applications is shown in Scheme 3. 

Heat a small amount of the potassium bromate in a test tube and detect the evolving oxygen. Write the equations of the reactions. 

Detection limit. A sensitive chromatographic method was developed to measure sub-part-per-billion levels of the disinfectant by-products iodate (I03), chlorite (C I02 ), and bromate (BrOf) in drinking water. As the oxyhalides emerge from the column, they react with Br to make Brj, which is measured by its strong absorption at 267 nm. For example, each mole of bromate makes 3 mol of Br by the reaction BrOj" + 8Br + 6H+ —> 3Brj + 3H20. 

Bromate near its detection limit gave the following chromatographic peak heights and standard deviations. The blank is 0 because chromatographic peak height is measured from the baseline adjacent to the peak. For each concentration, estimate the detection limit. Find the mean detection limit. 

The detection of new kinds of microorganisms, such as the cysts and oocysts of parasites (Giardia, Cryptosporidium), the identification of more and more chemical pollutants in waters and increasing quality levels required for drinking and waste waters has induced new interest in ozonation and ozone-based advanced oxidation processes. However, care has to be taken in the application of ozonation, since recent research has indicated that presumably hazardous by-products can be formed, e. g. bromate in the ozonation of waters containing bromide. 

The corresponding sodium salts, which are cheaper, serve equally well. Excess of potassium bromide and hydrochloric acid is added to a solution of the substance to be estimated and the bromate, in the form of a volumetric solution (usually N/5), is run in. The end point (shown by the presence of free bromine) is detectable, quite sharply, by spotting on starch-iodide paper as external indicator. Alternatively the end point may be determined by adding a known amount of bromate in excess, then potassium iodide, and titrating the liberated iodine with thiosulphate. 

Fig. 5. Strategies for isotope dilution analysis utilizing on-line coupling IC-ICP-MS. Shown is the separation of bromate and bromide by anion IC.The sample was 585 )Lll of a bottled water, spiked with bromate and a bromate isotope standard. The column, eluent and detection device are as described in Fig. 4. Shown are the mass traces form/z79 and 81 (dotted line) and the total time slice isotope ratio for m/z 79/81.

---