Bromide spectrophotometric method

Fukushima, R. S., and Hatfield, R. D., 2001, Extraction and isolation of lignin for utilization as a standard to determine lignin concentration using the acetyl bromide spectrophotometric method, J. Agric. Food Chem. 49 3133-3139. 

Discussion. In acid solution arsenic(III) can be oxidised to arsenic(V) and antimony(III) to antimony(V) by the well-established titration with a solution of potassium bromate and potassium bromide (Section 10.133). The end point for such determinations is usually observed indirectly, and very good results have been obtained by the spectrophotometric method of Sweetser and Bricker.23 No change in absorbance at 326 nm is obtained until all the arsenic)III) has been oxidised, the absorbance then decreases to a minimum at the antimony(III) end point at which it rises again as excess titrant is added. 

Harris et al. [8] has described methods for the determination of cyanide in these materials based on either spectrophotometry using p-phenylene diamine pyridine or gas chromatographically following conversion of cyanide to cyanogen bromide. Cyanide is extracted from the sample by digestion with phosphoric acid. Recoveries were in the range 96-99% (spectrophotometric method) and 90-96% (gas chromatographic method). 

Hassan, E.M. Determination of ipratropium bromide in vials using kinetic and first-derivative spectrophotometric methods. J. Pharm. Biomed. Anal. 21, 1183-1189 (2000)... 

Early colorimetric methods for arsenic analysis used the reaction of arsine gas with either mercuric bromide captured on filter paper to produce a yellow-brown stain (Gutzeit method) or with silver diethyl dithiocarbamate (SDDC) to produce a red dye. The SDDC method is still widely used in developing countries. The molybdate blue spectrophotometric method that is widely used for phosphate determination can be used for As(V), but the correction for P interference is difficult. Methods based on atomic absorption spectrometry (AAS) linked to hydride generation (HG) or a graphite furnace (GF) have become widely used. Other sensitive and specihc arsenic detectors (e.g., AFS, ICP-MS, and ICP-AES) are becoming increasingly available. HG-AES, in particular, is now widely used for routine arsenic determinations because of its sensitivity, reliability, and relatively low capital cost. 

The selectivity of spectrophotometric methods has been greatly increased by the development of derivative spectrophotometry (see Chapter 1.5). Derivative spectrophotometry enables one to single out, by means of various mathematical algorithms of data processing, a separate signal due to a selected component, from the sum of absorbances of the analysed mixture. This technique was successfully applied in determinations of a number of elements in mixtures such as Pd, Pt and Au [37], Pd and Pt in iodide solutions [38], Au, Pd and Pt in bromide solutions [39], Ru(IIl) and Rh(IIl) in the form of octadecyldithiocarbamate complexes [40], Ru and Os in chloride solutions [41], Cu, Hg and Pb as dithizonates [42], complexes of various metals with 4-(2-pyridylazo)resorcinol [43], Fe(IIl) with EDTA in the presence of Cr(III), A1 and Mn [44], Cr(III) and Cu(II) with EDTA [45], and Cu and Co in a flow system [46]. Derivative spectrophotometry was also used in the study of Sr- complexing reactions with various crown ethers [47]. 

Other inorganic reagents utilized in spectrophotometric methods are hydrogen peroxide (see determination of Ti, V, U, and Ce), SnCU ion (determination of platinum group elements [136]), iodide (see determination of Sb, Bi, and Pd), bromide (determination of Au), and also chloride and azide. 

Numerous spectrophotometric methods are based on the formation of ion-associates of the anionic iodide complex (CdL or Cdls ) [52-55] and bromide (CdBr4 ) [56] complexes with basic dyes. In the old flotation-spectrophotometric method (e = 1.3-10 ) [52], Crystal Violet is used, DIPE as floating solvent and acetone for dissolution of the floated compound. Other dyes that have been used in association with the cadmium iodide complex include Rhodamine 6G [57], Malachite Green (extraction with benzene) [53,54], and a basic azo dye [55]. 

Recently, two very sensitive flotation-spectrophotometric methods, based on adducts composed of the ion-associates Methylene Blue (MB)-Aul2 or Rhodamine 6G (R6G)-AuBr4, and the salts MB-I3 or RbG-Brs , respectively, have been proposed. In the iodide system, the ratio Au MB = 1 4 (e = 3.4-10 ) [30], and in the bromide system Au R6G =1 13 (e= 11.4-10 ) [21]. 

Methods for Pd determination based on ion-associates with basic dyes are often very sensitive. In extraction-spectrophotometric methods, thiocyanate [84-89], chloride, and bromide [84] anionic complexes of palladium are associated with Brilliant Green [84], Malachite Green [85,88], Rhodamine B (e = 9.0-10 ) (86), Rhodamine 6G [89], and Methylene Blue [87]. In flotation-spectrophotometric methods, ion-associates formed by the... 

Sensitive extraction-spectrophotometric methods are based on the extractable (into CHCI3, 1,2-diehloroethane, benzene, or toluene) ion-associates of basic dyes and anionic Ag complexes with cyanide [35,36], iodide [37,38], and bromide [39]. In these methods, use has been made of such dyes as Crystal Violet [35,39], Brilliant Green [38,39], Malachite Green [39], Methylene Blue [36], and Nile Blue A [37]. In some of these methods the molar absorptivities are elose to MO [36,39]. A flotation method has been proposed, based on the addition compound [R6G ][Ag(SCN )2] [R6G ][SCN ] which is formed by silver ions (at pH 2-5) in the presence of thiocyanate and Rhodamine 6G (flotation with DIPE, the precipitated compound is washed and dissolved in acetone, e = 1.5-10 ) [40]. The complex Ag(CN)2 , associated with Crystal Violet, has been utilized in another flotation-spectrophotometric method of determining silver [41]. Silver has been determined also in a system comprising thiocyanate and Rhodamine B, as an aqueous pseudo-solution, in the presence of poly(vinyl alcohol) [42]. 

The reaction between Tl(III) bromide and cw-syn-cis-dicyclohexano-18-crown-6 immobilized on silica gel was studied [2]. Sorption-spectrophotometric method for the determination of T1 (3 0.05 mg 1" ) the presence of heavy metal ions has been proposed. 

This spectrophotometric method is based on the binding of a carbocyanine dye (1 -ethyl-2-[3-( 1 -ethyl-naphto[ 1,2rflthiazolin-2-ylidene)-2-methyl-propenyl]naphto [l,2rflthiazolium bromide, Stains all) to undegraded hyaluronan [34]. The unit of enzyme activity is defined as the amount of enzyme that will produce a 10% decrease in the absorbance of the dye-hyaluronan complex after one hour of incubation. 

Shapovalov has reported the results of a study of the effects of continuous exposure to elemental bromine, bromides, and methyl bromide on the functions of liver and thyroid gland, and on haematological change, in 140 workers. Spectrophotometric methods have been used to obtain the rate law and other parameters at 298.2 K for Br2 HCN BrCN + H Br. Sill has discussed the... 

The advantage of discrete analyzers is that sample crossover in the system itself is the lowest possible. Volumes of 75 pi of reagent and sample volumes as large as 100 pi are sufficient. In an automated system with a throughput of 200 determinations per hour in the same sample 6 to 10 components (such as ammonium, alkalinity, aluminum, boron, bromide, calcium, chloride, chromium(VI), cyanide, fluoride, iron, magnesium, nitrate, nitrite, phosphate, etc.) can be determined. In discrete analyzers normally conventional spectrophotometric methods are used. These methods are prone to interference of the matrix of the sample. As a good concept for interference studies still is not available, interferences are as yet not sufficiently studied systematically even for routine analyses. 

Another spectrophotometric method is based on the reaction of bromide ions with triphenylmethane dyes in the presence of chloramine B, chloramine T, or NaClO. The... 

Generally, methods are based on solvent extraction of the additive followed by analysis for the extracted additive by a suitable physical technique such as visible spectrophotometry of the coupled antioxidant, redox spectrophotometric methods, ultraviolet spectroscopy, infrared spectroscopy, gas chromatography, thin-layer chromatography or column chromatography. In general, direct chemical methods of analysis have not foimd favour. These include potentiometric titration with standard sodium isopropoxide in pyridine medium or reaction of the antioxidant with excess standard potassium bromide-potassium bromate (ie. free bromine) and estimation of the unused bromine by addition of potassium iodide and determination of the iodine produced by titration with sodium thiosulphate to the starch end-point. ... 

The interaction between bromide and lanthanide ions was also studied, but experimental data are available for aqueous methanol solutions only (Kozachenko et al. 1973). Using a spectrophotometric method, the formation of rather weak outer-sphere bromo complexes was evidenced, and their stability constants for Pr, Nd, Sm, and Ho were determined in water and in 50% and 90% methanol (table 3). For solutions in 50% methanol, the stability of the outer-sphere bromo complexes is larger for Pr, Nd, and Sm Ki = 1.3—1.9) compared to Ho (0.97) and Er (0.70). Kozachenko et al. (1973) explained this behaviour as reflecting a higher stability for the solvates of the heavier lanthanide ions. A similar trend was observed in the stability constants of the chloro complexes in absolute methanol vide supra). Finally, the stability of the bromo complexes of the lanthanides increases as the dielectric constant of the medium is reduced. 

Other detection methods are based on optical transmittance [228-231], Alcohol sulfates have been determined by spectrophotometric titration with barium chloride in aqueous acetone at pH 3 and an indicator [232] or by titration with Septonex (carbethoxypentadecyltrimethylammonium bromide) and neutral red as indicator at pH 8.2-8.4 and 540 nm [233]. In a modified two-phase back-titration method, the anionic surfactant solution is treated with hyamine solution, methylene blue, and chloroform and then titrated with standard sodium dodecyl sulfate. The chloroform passing through a porous PTFE membrane is circulated through a spectrometer and the surfactant is analyzed by determining the absorbance at 655 nm [234]. The use of a stirred titration vessel combined with spectrophotometric measurement has also been suggested [235]. Alternative endpoint detections are based on physical methods, such as stalag-mometry [236] and nonfaradaic potentiometry [237]. 

The basis of this method is that when normal seawater is chlorinated at the usual levels of 1 to 10mg/l of chloride, the bromine in seawater (8.1 x 10 4 M, 65 mg/1 at salinity = 35%o) is rapidly and quantitatively oxidised to Br() and HBrO. If 50 mg/1 of bromide is added to distilled or fresh waters containing HCIO plus C1CT, then HBrO plus BrO" are both formed. The HBrO plus BrO" will in turn rapidly brominate fluorecein (9-[o-carboxyphenyl]-6-hydroxy-3-isoxanthenone) to give the pink tetrabromo derivative eosin yellow (2,4,5,7-tetrabromo-9-[o-carboxyphenyl]-6-hydroxy-3-isoxanthenone), provided the molar ratio of bromide to fluorescein is 4 1. The resultant increase in eosin can be measured visually or spectrophotometrically, and the decrease in fluo-roscein measured fluorometrically. If the molar ratio of bromide to fluoroscein is < 4 1, then the mono-, di-, and tri-bromo derivatives are formed repro-ducibly. These derivatives have extinction coefficients close to eosin and are accounted for in the standardisation. 

Le Corre and Treguer [49] developed an automated procedure based on oxidation of the ammonium ion by hypochlorite in the presence of sodium bromide followed by spectrophotometric determination of the nitrite. The standard deviation on a set of samples containing 1 p,g NH -N per litre was 0.02. This method was compared with an automated method for the determination of ammonia as indophenol blue. The results from the two methods are in good agreement. 

The MTT method is simple, accmate and yields reproducible results. The key component is (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) or MTT. Mitochondrial dehydrogenases of viable cells cleave the tetrazolium ring, yielding prrrple formazan crystals insolnble in aqueous solutions. The crystals are dissolved in acidified isopropanol. The resrrlting ptuple solution is measured spectrophotometrically. An increase or decrease in cell number results in a concomitant... 

All data obtained on the rate of reaction of [Ni(NiL2)2]Cl2 with alkyl halides— i.e., methyl iodide, benzyl bromide, benzyl chloride, p-nitrobenzyl chloride, p-chlorobenzyl chloride, ethyl bromide, ethyl iodide, n-propyl bromide, and n-propyl iodide—conform closely to a pseudo-first-order rate law. Almost all experiments were carried out in the presence of an excess of alkyl halide. Since methanol solutions of the alkylated complexes have only negligible absorption at 495 m//, rates were obtained by graphs of log A0—A vs. time. The graphs are linear over the entire time interval, which corresponds to more than two half lives in most cases, passing through the origin at zero time. The rate is essentially the same whether measured by the spectrophotometric or conductivity method. 

In this reversed phase high performance liquid chromatographic method for neutral and cationic metal chelates with azo dyes, tetraalkylammonium salts are added to an aqueous organic mobile phase. The tetraalkylammonium in salts are dynamically coated on the reversed stationary support. As a result of the addition of tetraalkylammonium salts, the retention of the chelates is remarkably reduced. Tetrabutylammonium bromide permits rapid separation and sensitive spectrophotometric detection of the vanadium(V) chelate with 2-(8-quinolylazo)-5-(dimethylamino)-phenol, making it possible to determine trace vanadium(V). 

Other indirect methods involve reactions with the mercury(II) complexes of diphenylcarbazone [20] or Methylthymol Blue [21], or the displacement of thiocyanate ion from AgSCN or Hg(SCN)2 by bromide, followed by the spectrophotometric determination of thiocyanate with ferric ions [22,23]. 

In another method proposed, the bromide is oxidised to BrOs" by the action of persulphate [24,25]. After complete decomposition of the oxidizer, iodide is added in excess and the equivalent amount of iodine, formed in reaction with the BrOs", is determined spectrophotometrically at 355 nm (e = 7.3-10 ). 

The first enzyme electrode-based lactate analyzer was developed in 1976 by La Roche (Switzerland) (see Table 23). It uses cytochrome b2 in a tiny reaction chamber on top of a platinum electrode polarized at +0.25-0.40V. The solution for blood sample pretreatment recommended by the manufacturer has been improved by Soutter et al. (1978) by addition of cetyltrimethylammonium bromide. This compound hemo-lyzes the sample, stabilizes the lactate content, and leads to a good correlation with the spectrophotometric reference method using deproteinized blood ... 

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