Spectrofluorimetric determination of traces of bromide

A Spectrofluorimetric method for the determination of traces of bromide has been developed. The method is based on the bromination of fluorescein after bromide and hypochlorite form bromine, giving the less fluorescent eosin. The fluorescence decrease is used as the analytical signal. The calibration graph is linear over the range 10 to 80 g/1. The detection limit is 3 g/1 and the relative standard deviation 1.0%. The method has been satisfactorily applied to the determination of bromide in natural waters.     

Indirect polarographic microdetermination of chlorine or bromine in organic compounds

A polarographic method for the microdetermination of chlorine or bromine in organic compounds is based on oxygen-flask combustion followed by an exchange reaction of chloride or bromide with excess of solid silver chromate, and polarographic determination of the chromate liberated. The method has been applied satisfactorily to a wide range of chlorine or bromine organic compounds with a coefficient of variation not exceeding 1%.     

Regioselective bromination of (Tetraphenyltetrabenzoporphyrinato)palladium(II). Synthesis of a new octabromo derivative of the tetraphenyltetrabenzoporphyrin series

Bromination of (meso-tetraphenyltetrabenzoporphyrinato)palladium(II) with bromine in the presence of tetramethylammonium bromide occurs exclusively at the benzene rings fused to the porphyrin system while the phenyl rings in the meso positions are not involved. The corresponding octabromo-substituted complex was obtained using a large excess of bromine on prolonged reaction time. The complex was isolated and characterized by ¹H NMR spectra, electronic absorption spectra in the UV and visible regions, and MALDI-TOF mass spectra. It was assigned the structure of symmetric (22,23,72,73,122,123,172,173-octabromo-5,10,15,20-tetraphenyltetrabenzoporphyrinato)palladium(II).     

Three useful bromimetric methods for the determination of salbutamol sulfate

Three different methods developed for the determination of salbutamol sulfate (SBS), in pure drug form and in dosage forms, are discussed. The methods are based on the oxidation–bromination reaction of the drug by bromine generated in-situ by the interaction of bromate with bromide in acid medium. In titrimetry the drug is titrated directly with bromate in the presence of a large excess of bromide and in sulfuric acid medium using methyl red as indicator. Spectrophotometry is based on addition of a measured excess of bromate–bromide mixture to the sample solution in sulfuric acid medium followed by the estimation of surplus bromine by reacting it with a definite amount of methyl orange dye and measuring the absorbance at 510 nm. The amount of bromate reacting corresponds to the sample content. The kinetic method depends on the linear relationship between the concentration of the drug and time for oxidation and bromination as indicated by the bleaching of the methyl orange acid colour by the bromine generated in situ. Titrimetry is applicable in the 2–20 mg range. In spectrophotometry, Beer's law is obeyed in the 0.5–5.0 g mL^–1 range whereas concentrations in the 5.0–25.0 g mL^–1 range can be determined by the kinetic method. The effect of common excipients and additives in tablets is discussed. The procedures have been successfully applied to dosage forms; the results agree well with those obtained by use of a reference method. The methods can be used to determine SBS at mg or g levels.     

Determination of bromine in organic compounds by high-performance liquid chromatography

A method is proposed for the determination of bromine in organic compounds (which may also contain chlorine and iodine) by oxygen-flask combustion of the compound followed by pre-column reaction of bromide with acetanilide and 2-iodosobenzoic acid to form 4-bromoacetanilide which is then chromatographed on an ODS column with a mobile phase of methanol: water, 65:35 v/v, detection at 240 nm, and 4-N-acetylaminotoluene as internal standard. The method is rapid and precise (RSD 相似文献   

Determination of Nitrite via Reaction with Pyridine-4-Carboxylic Acid Hydrazide

Abstract

Nitrite is determined by its reaction with a measured but excessive amount of pyridine-4-carboxylic acid hydrazide in acid medium (when the two substances react in a 1:1 molar ratio) and evaluation of the surplus hydrazide by titration with chloramine-T in the presence of acidified potassium bromide, the end-point being shown by the decolorization of the methyl red indicator. Nitrate, copper(II), mercury(II), etc. are found not to interfere, and the determination of nitrite in the presence of diazotized aromatic amines is demonstrated.     

Fission reactions of the aziridine ring

Reaction of N-arylethylenimines with carbon dioxide in the presence of tetraethylammonium bromide gives N-aryl-2-oxazolidones, with N,N-diarylpiperazines as by-products. Carbon disulfide reacts with N-arylethylenimines under similar conditions to give 11 copolymers, together with small amounts of N-arylthiazolidine-2-thiones. Carbon oxysulfide gives copolymers only. The copolymers are converted at 250° C into N-arylthiazolidine-2-thiones and N-arylthiazolidones, respectively. N-Arylethylenimines react with phenyl isothiocyanates to give 2-phenylimino-3-arylthiazolidines.For part III, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 5, pp. 611–615, May, 1970.     

Reaction of Some Dibromomethyl-Substituted Cyclohexadienones with Molecular Bromine

4-Dibromomethyl-4-methyl-2,5-cyclohexadienone and its 2- and 3-methyl-substituted derivatives react with an equimolar amount of molecular bromine in carbon tetrachloride, yielding vinyl bromination products at the -position with respect to the carbonyl group. The reaction of 4-dibromomethyl-3,4-dimethyl-2,5-cyclohexadienone with a large excess of bromine, apart from the vinyl bromination product, gives the corresponding 3-bromomethyl and 3-dibromomethyl derivatives. 4-Dibromomethyl-2,4-dimethyl-2,5-cyclohexadienone takes up bromine molecule at the C ² ÍC ³ double bond.     

Indirect complexometric determination of palladium(II) using sodium nitrite as a selective masking reagent

A selective complexometric method is described for the determination of palladium, sodium nitrite being used as masking reagent. Palladium(II) in a given sample solution is initially cornplexed with an excess of EDTA and the surplus EDTA is titrated with zinc sulfate solution at pH 4.5–5.5 (acetic acid-sodium acetate buffer), using xylenol orange as indicator. An excess of sodium nitrite is then added, the mixture is shaken well and the EDTA released from the Pd-EDTA complex is titrated with a standard zinc sulfate solution. Results are obtained for 2.5–27.5 mg of Pd with relative errors 0.5% and standard deviations 0.05 mg. The interferences of various ions are studied. The method is applied for the determination of palladium(II) in alloys and complexes.     

Determination of nitrite as pentafluorobenzyl derivative by RP-HPLC and UV detection with and without ion-pair extraction

Summary A reversed-phase high-performance liquid chromatographic (RP-HPLC) method with UV detection (270 nm) for the determination of nitrite as its pentafluorobenzyl derivative with and without ion-pair extraction is described. Ion-pair extraction of nitrite from aqueous solutions was performed by using a 1 mol/l solution of the liquid ion exchanger methyltrioctylammonium chloride in toluene. The residue of the ion-pair extraction or an aliquot of an aqueous nitrite solution or of a biological fluid (100 l) were treated with 400 l of acetone and 10 l of pentafluorobenzyl bromide. Nitrite was converted into its pentafluorobenzyl derivative by heating at 50°C for 90 min. After evaporation of acetone the aqueous phases were diluted with 100 to 400 l of methanol, and up to 100 l were injected into the RP-HPLC system. The method allows accurate analysis of nitrite in the presence of nitrate directly in aqueous solutions and biological fluids in concentrations down to 2.0 mg/l. The method is also applicable to the determination of nitrate following its reduction to nitrite by cadmium.     

Determination of nitrite and mixtures of bromide and iodide with o-iodosobenzoate

Nitrite diazotizes sulphanilamide, which then does not undergo 3,5-dibromination. Nitrite can therefore be determined by reaction with excess of sulphanilamide, the surplus of which is then titrated with o-iodosobenzoate or chloramine-T in the presence of potassium bromide, with Methyl Red as indicator. Mixtures of iodide and bromide can be analysed by oxidation of the iodide with excess of o-iodosobenzoate at pH 4-6, followed by extraction of the iodine (which is then titrated with thiosulphate) and then oxidation of the bromide in dilute sulphuric acid medium in the presence of sulphanilamide as bromine scavenger, the residual oxidant being evaluated iodometrically.     

β-环糊精增敏亚甲基蓝荧光法测定左氧氟沙星

提出了一种增敏亚甲蓝荧光法测定左氧氟沙星新方法。左氧氟沙星(LVFX)与Br2发生加成反应,剩余的Br2能氧化亚甲蓝(MB)使其荧光降低,通过测定亚甲蓝的荧光强度间接测定左氧氟沙星(LVFX)的含量,加入适量β-环糊精(β-CD)使其荧光强度上升为原来的近2倍,大大提高其灵敏度。该体系最大激发波长为λex=660 nm,最大发射波长为λem=678 nm,线性范围为0.002～1.6 mg/L,检出限为0.0008 mg/L,相对标准偏差为0.13%。本方法可作为痕量左氧氟沙星的分析方法。     

Coulometric titration of benzoic and isonicotinic acid derivatives of hydrazides and acylhydrazones

It was found that benzoic acid hydrazides rapidly and quantitatively react with electrogenerated chlorine and bromine under the conditions of galvanostatic coulometry. Benzoic acid hydrazides were determined in model solutions. A good precision (RSD varied from 1 to 6%) allowed coulometry to be applied to the determination of isonicotinic acid hydrazide in isoniazid tablets and isonicotinic acid 3-methoxy-4-hydroxybenzylidenehydrazide in phthivazid tablets.     

Utilization of bromination reactions for the determination of carbamazepine using bromate–bromide mixture as a green brominating agent

One titrimetric and two spectrophotometric procedures have been developed for the assay of carbamazepine (CBZ) in bulk drug, formulations and spiked human urine. The methods are based on the bromination of CBZ by the bromine generated in situ by the action of the acid on the bromate–bromide mixture. The twin advantages of avoiding liquid bromine and analysis in a cost-effective manner are realized. In titrimetry, the drug was treated with a known excess of bromate–bromide mixture in hydrochloric acid medium followed by the determination of unreacted bromine iodometrically. Spectrophotometry involves the addition of a measured excess of bromate–bromide reagent in acid medium to CBZ, and after the reaction is ensured to be complete, the residual bromine was determined by reacting with a fixed amount of either methyl orange and measuring the absorbance at 510 nm (method A) or indigo carmine and measuring the absorbance at 610 nm (method B). Titrimetric procedure is applicable over the range of 1.00–7.50 mg CBZ, and the calculations are based on a 1:1 reaction stoichiometry (CBZ:KBrO₃). In spectrophotometric methods, Beer’s law is valid within concentration ranges of 0.25–1.50 and 0.50–6.00 μg ml⁻¹ CBZ for methods A and B, respectively. The proposed methods were successfully applied to the determination of CBZ in tablets and syrup, in addition to spiked human urine by the spectrophotometric methods, with mean recoveries of 95.50–104.0% and the results were statistically compared with those of an official method by applying Student’s t-test and F-test.     

Analysis of organobromine compounds and HBr in motor car exhaust gases with a GC/microwave plasma system

Summary In this investigation an analytical procedure for the determination of different organobromine compounds in motor car exhaust gases is developed in order to obtain a total balance of these compounds in this type of exhaust gas. For this purpose, adsorption sampling on Tenax GC combined with thermal desorption and a fast cold trap injection into the GC column system is used. A special capillary cold trap/thermodesorption system for a fast injection within 1 s is developed. The chromatographically separated fractions are identified by their retention times and elementspecific detection with a microwave plasma detector. Methyl bromide, 1,2-dibromoethane, and vinyl bromide are analysed in exhaust gases in cases where the gasoline contains 1,2-dibromoethane as an additive (leaded gasoline). The analysed bromine contents, which correspond to these organobromine compounds, are in the range of 90–190 g/m³, 15–85 g/m³, and 5–20 g/m³, respectively. The portion of the organobromine compounds is 22–44% of the total bromine which is emitted by the exhaust gases. The other portion contains mainly inorganic particulate bromide, which can be separated by filters. The concentration of the organobromine compounds decreases with increasing motor temperature. After conversion into 2-bromocyclohexanol and after gas chromatographic separation HBr is detected to be 5.8 g bromine per m³ exhaust gas, which corresponds to approximately 1% of the total bromine emission. 1,2-Dichloroethane is analysed in the range of 5–35 g Cl/m³, whereas the concentration of tetraalkyl lead in the exhaust gases is less than the detection limit of 6.7 g Pb/m³. The average bromine/lead ratio found in the filterable portion of the exhaust gases is 0.30 (by weight); the same ratio calculated for total bromine emission including the organobromine compounds is 0.47. Compared with the bromine/ lead ratio in gasoline of 0.39 this means that at least 17% of the total lead in the gasoline is not directly emitted with the motor car exhaust gases.

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Analyse von bromorganischen Verbindungen und HBr in Autoabgasen mit einem GC/Mikrowellenplasma-System

     

室温下二氧化氮催化带有给电子取代基的苯和萘的氧化溴化

在室温下,以8.2%的二氧化氮为催化剂,反应管中残留的空气为氧化剂,分子溴为溴化试剂,研究了带有给电子取代基的苯和萘的氧化溴化.使用的低沸点非金属催化剂易于从产物中去除,很少玷污最终产品;但反应后有少量的苯环硝化副产物生成,这会造成催化剂二氧化氮的损耗.反应具有较高的原子经济性,大部分溴原子被转化到产物中.反应产物具有可控性:可通过改变溴源的用量,分别得到单溴化和二溴化产物.初步的机理分析结论为:反应可能经历分子溴和芳环的反应,生成溴代芳烃和溴化氢;然后在氧化氮类物种催化下,生成的溴化氢被氧气氧化为具有反应活性的溴.     

Rapid titrimetric and spectrophotometric assay methods for the determination of lamivudine in pharmaceuticals using iodate and two dyes

One titrimetric and two spectrophotometric methods, which are simple, sensitive and rapid, are described for the assay of lamivudine in bulk drug and in tablet dosage forms using potassium iodate and two dyes, methyl orange and indigocarmine, as reagents. In titrimetry, an aqueous solution of lamivudine is titrated directly with iodate in an acidic medium, and in the presence of an excess of bromide using methyl orange as an indicator. After the decoloration of the red color of methyl orange, the residual bromine is titrated iodometrically to a starch endpoint. Spectrophotometric methods involve the addition of a known excess of iodate in an acidic medium and in the presence of an excess of bromide followed by the determination of residual bromine by the reaction with a fixed amount of either methyl orange and measuring the absorbance at 520 nm (method A), or indigo carmine and measuring the absorbance at 610 nm (method B). In all methods, the amount of iodate which reacted corresponds to the amount of lamivudine content. The titrimetric method is applicable over the 1.5–8.0 mg range. The systems obey Beer’s law for 0.5–5.0 μg/mL (method A) and 1.25–12.5 μg/mL (method B). The calculated apparent molar absorptivity values are found to be 3.3 × 10⁴ and 9.3 × 10³ L mol⁻¹ cm⁻¹, for method A and method B, respectively, and the corresponding Sandell sensitivity values are 6.94 and 24.62 ng/cm². The limits of detection and quantification are also reported for both spectrophotometric methods. Intra-and interday precision and accuracy for the developed methods have been evaluated. The methods were successfully applied to the assay of lamivudine in tablet form and the results were compared with those of a reference method by applying the Student’s t-test and F-test. No interference was observed from common tablet adjuvants. The accuracy and reliability of the methods were further ascertained by recovery experiments using the standard addition technique. The text was submitted by the authors in English.     

Titrimetric determination of some organic compounds with bromine chloride

Bromine chloride is used in hydrochloric acid medium as a standard reagent for the rapid and precise determination of organic compounds by direct or indirect titrimetric methods. Hydrazine and its aryl derivative undergo a 4-electron change. Carbonyl compounds are determined by reaction with excess of 2,4-dinitrophenylhydrazine and estimation of the surplus. Sulphanilamide undergoes a substitution reaction in 1:3 molar ratio to bromine chloride. Thiobarbituric acid and thiourea or its alkyl derivatives show an 8-electron change but aryl thioureas also undergo nuclear bromination. Thiosemicarbazide and semicarbazide give a 10- and a 2-electron change respectively. In the direct titration, methionine is oxidized to its sulphoxide whereas cystine and cysteine form cysteic acid. In presence of bromide, glutathione forms the sulphonic acid but in the presence of iodide the product is the disulphide. The analytical results obtained by bromine chloride method are compared favourably with those afforded by established procedures.     

Simultaneous determination of bromide, nitrite and nitrate ions in seawater by capillary zone electrophoresis using artificial seawater as the carrier solution

We describe capillary zone electrophoresis (CZE) for the simultaneous determination of bromide, nitrite and nitrate ions in seawater. Artificial seawater was adopted as the carrier solution to eliminate the interference of high concentrations of salts in seawater. The artificial seawater was free from bromide ion to enable the determination of bromide ion in a sample solution. For the purpose of reversing the electroosmotic flow (EOF), 3 mM cetyltrimethylammonium chloride (CTAC) was added to the carrier solution. A 100 microm ID (inside diameter) capillary was used to extend the optical path length. The limits of detection (LODs) for bromide, nitrite, and nitrate ions were 0.46, 0.072, and 0.042 mg/L (as nitrogen), respectively. The LODs were obtained at a signal to noise ratio (S/N) of 3. The values of the relative standard deviation (RSD) of peak area for these ions were 1.1, 1.5, and 0.97%. The RSDs of migration time for these ions were 0.61, 0.69, and 0.66%. Artificial seawater samples containing various concentrations of bromide, nitrite, and nitrate ions were analyzed by the method. The error was less than +/-12% even if the concentration ratio of bromide ion to nitrite or nitrate ion was 20-240. The proposed method was applied to the determination of bromide, nitrite, and nitrate ions in seawater samples taken from the surface and the seabed. These ions in other environmental waters such as river water and rainwater samples were also determined by ion chromatography (IC) as well as this method.     

Titrimetric microdetermination of isoniazid by amplification reactions

An amplification method for the determination of (0.01–2.0 mg) isoniazid is described. It depends on oxidation of the isoniazid sample solution with a chloroform solution of iodine and removed of its excess, oxidation of the resulting iodide with bromine, and iodometric titration of the liberated iodate after 6-fold amplification. Alternatively, the liberated iodine is reduced to iodide, and again oxidized to yield 36 iodide ions for every iodide ion originally present. The coefficient of variation does not usually exceed 1.5% for above 0.5 mg of isoniazid but increases to 3.6% at the 0.01-mg level.