Volumetric studies in oxidation-reduction reactions: Reduction with ferrous ethylenediamine sulphate ceric sulphate method

Ferrous ethylenediamine sulphate has been used as a reducing agent in acid medium for the indirect volumetric estimations of potassium chlorate, potassium bromate, potassium metaperiodate, potassium dichromate, potassium ferricyanide, potassium permanganate, potassium persulphate, hydrogen peroxide and ceric sulphate. The excess of ferrous ethylenediamine sulphate added to each of the substances in acid medium was titrated with standard ceric sulphate solution using ferroin as an indicator.     

Potentiometric studies in oxidation-reduction reactions: Reduction with ferrous ethylenediamine sulphate ceric sulphate method

Ferrous ethylenediamine sulphate has been used as a reducing agent to determine indirectly potassium permanganate, ceric sulphate, potassium chlorate, hydrogen peroxide, potassium persulphate, potassium dichromate and potassium bromate by a potentiometric method. An excess of ferrous ethylenediamine sulphate added to each of the substances in acid medium was titrated with a standard solution of ceric sulphate, using platinum foil as an oxidation-reduction electrode coupled with a saturated calomel electrode through an agar-agar potassium chloride bridge.     

Potentiometric studies in oxidation-reduction reactions: Reduction with ferrous ethylenediamine sulphate indirect determinations

Ferrous ethylenediamine sulphate has been used as a reducing agent to determine indirectly potassium dichromate, hydrogen peroxide, potassium permanganate, potassium persulphate, potassium chlorate, potassium bromate, and ceric sulphate by a potentiometric method. An excess of ferrous ethylenediamine sulphate added to each of the substances in an acid medium is titrated with a standard solution of potassium permanganate, using platinum foil as an oxidation-reduction electrode coupled with a saturated calomel electrode through an agar-agar potassium chloride bridge.     

Vanadametry Estimation of Thiosulphate

1.(a) We have found that sodium thiosulphate is quantitatively oxidized to tetrathionate in five minutes at room temperature (28°) by excess sodium vanadate in a medium containing sulphuric acid at 0.06N to 0.1N concentration and a little copper sulphate as catalyst. (b) Quantitative emulation of sodium thiosulphate to tetrathionate has also been achieved by the action of excess sodium vanadate during five minutes at room temperature in a medium containing 2.0N—8.0N acetic acid and a little copper salt as catalyst. Further oxidation to sulphate does not occur, even if the mixture is heated to boiling. (c) The excess of unreacted vanadate in 1(a) and 1(b) can be titrated with a standard solution of ferrous ammonium sulphate using diphenylbenzidine as indicator, after adding the requisite quantity of syrupy phosphoric acid. 2. On the other hand, sodium thiosulphate is easily and quantitatively oxidized to sulphate at room temperature, when. acted upon by excess sodium vanadate in a medium containing hydrochloric acid at an overall concentration of 5-6N and 1.0 ml of iodine monochloride as catalyst. The time required for reaction is ten minutes. The unreacted vanadate can be estimated by titration with a standard solution of ferrous ammonium sulphate, using N-phenylanthranilic acid as indicator or with diphenylbenzidine as indicator after suitably diluting and adding phosphoric acid.     

Sodium meta-vanadate as volumetric reagent : Iodine monochloride method

Sodium meta-vanadate has been used as an oxidising agent in hydrochloric acid medium for the volumetric estimations of potassium iodide, sodium arsenite, mercurous chloride, potassium thiocyanate, sodium sulphite, sodium bisulphite, sodium thiosulphate, ferrous sulphate and hydrazine sulphate, using iodine monochloride as a catalyst and preoxidiser. Chloroform is used as an indicator. It is coloured pink due to the liberation, of iodine during the titration and becomes light pale yellow at the end-point due to the formation of iodine monochloride.     

Photoprocesses in sodium decyl sulphate micellar media

The absorption and fluorescence behaviour of thionine dye in sodium decyl sulphate (sds) medium has been studied in detail. The transient spectra and kinetics of decay of semithionine species produced by photoreduction of thionine by ferrous ions has-been studied using flash photolysis technique. The results have been compared with those in neat aqueous medium and in sodium lauryl sulphate (sls) media published earlier. It was found that the decay of semithionine which is kinetically second order in neat aqueous medium becomes pseudo first order as in thesls medium; however unlike in the latter case, the pseudo first order rate decreases with increasing surfactant concentration at all concentrations of ferric ion. The effect of electrolyte concentration on transient semithionine spectra and decay kinetics has also been studied. It was found that with increasing NaCl concentration the transient absorbance decreases and the decay slowly reverts back to second order as in aqueous medium. Insds medium as compared tosls a much higher concentration of NaCl is needed for the reaction to become second order which is attributed to stronger binding of ferric ions to thesds micelles.     

Potassium meta-periodate as volumetric reagent : Iodine bromide method

Potassium meta-periodate has been used as an oxidising agent in acid medium for the volumetric estimationss of potassium iodide, arsenious oxide, antimonous oxide, stannous chloride, mercurous chloride, sodium sulphite, sodium thiosulphate, sodium tetrathionate, ferrous sulphate, potassium thiocyanate, hydrazine sulphate, phenylhydrazine hydrochloride and hydroquinone by the iodine bromide method. Carbon tetrachloride is used as an indicator. It is coloured pink during the titration. and becomes colourless at the end-point due to the formation of stable iodine bromide complex IBr2-, which does not dissociate, in the presence of a large excess of bromide ion.     

Volumetric studies in oxidation-reduction reactions: Reduction with ferrous ethylenediamine sulphate indirect determinations

Ferrous ethylenediamine sulphate has been. used as a reducing agent in acid medium for the indirect volumetric estimations of potassium chlorate, potassium bromate, potassium metaperiodate, potassium, dichromate, potassium ferricyanide, potassium permanganate, potassium persulphate, hydrogen peroxide and ceric sulphate. The excess of ferrous ethylenediamine sulphate added to each of the substances was titrated with standard potassium permanganate and also with. standard potassium dichromate solution. In case of potassium bromate or potassium metaperiodate the end-point was not sharp in potassium dichromate titrations; while accurate volumetric observations were made with standard potassium permanganate solution.     

Sodium hypochlorite as volumetric reagent

Summary In presence of 5 N to 6 N hydrochloric acid, ferrous ethylenediamine sulphate was used as a reducing agent to determine indirectly potassium chlorate, potassium bromate, potassium metaperiodate, potassium dichromate, potassium ferricyanide, potassium permanganate, potassium persulphate, hydrogen peroxide, ceric sulphate and chloramine-T. An excess of ferrous ethylenediamine sulphate added to each of the substances in the acid medium was titrated with a standard solution of sodium hypochlorite. Iodine monochloride was used as catalyst and preoxidizer and chloroform was used as an indicator. Chloroform was coloured violet owing to the liberation of iodine during the titration and became very pale yellow at the end-point because of the formation of iodine monochloride.Part I: See Z. analyt. Chem. 160, 429 (1958).     

Titrimetric and spectrophotometric assay of pantoprazole in pharmaceuticals using cerium(IV) sulphate as oxidimetric agent

Titrimetric and spectrophotometric assay of pantoprazole sodium sesquihydrate (PSS) using cerium(IV) sulphate as the oxidimetric reagent is described. The methods are based on the oxidation of PSS with a measured excess of Ce(IV) sulphate followed by the determination of unreacted oxidant using different reaction schemes. In titrimetry, the unreacted oxidant was determined by back titration with ferrous ammonium sulphate (FAS) in sulphuric acid medium. Spectrophotometry involves the reduction of unreacted Ce(IV) sulphate with a fixed quantity of Fe(II). The resulting Fe(III) is complexed with thiocyanate and the absorbance is measured at 470 nm. In both the methods, the amount of Ce(lV) sulphate reacted corresponds to PSS concentration. Titrimetry is applicable over 1–10 mg range whereas in spectrophotometry, the calibration graph is linear in the range of 0.5–7.0 μg/mL and the calculated molar absorptivity value is 1.58 × 10⁵ L/mol cm. The validity of the proposed methods was tested by analyzing pure and dosage forms containing PSS. Statistical treatment of the results reflects that the proposed procedures are precise, accurate and easily applicable to the determination of PSS in pure form and in pharmaceutical formulations.     

硫酸亚铁对化学沉积钴-铁-磷合金中的影响(英文)

在以次亚磷酸钠为还原剂、硼酸为缓冲剂和柠檬酸钠为络合剂的碱性介质中,化学沉积钴 铁 磷合金和钴 磷合金.研究了沉积工艺,如pH值和主盐CoSO4/FeSO4的摩尔比对沉积速率的影响.发现镀液中的硫酸亚铁对钴 铁 磷合金沉积有阻碍作用,以致其沉积速率比钴 磷的低.电化学极化实验表明,硫酸亚铁既影响阳极过程又影响阴极过程,它降低了两者的极化电流和极化电势.电化学实验结果与沉积速度测量结果基本相符.     

Chemiluminescence high-performance liquid chromatography for the determination of hyaluronic acid, chondroitin sulphate and dermatan sulphate.

A sensitive chemiluminescence high-performance liquid chromatographic method has been developed for the determination of hyaluronic acid, chondroitin sulphate and dermatan sulphate as their unsaturated disaccharide-dansylhydrazine derivatives involving an effective sample clean-up system. The dansylhydrazones of the unsaturated disaccharides derived from the hyaluronic acid, chondroitin sulphate and dermatan sulphate by chondroitinase ABC and/or chondroitinase ACII, were separated by reversed-phase chromatography using a mixture of 0.1 M sodium acetate buffer (pH 6.0) and 80% acetonitrile on a column (250 mm x 4.0 mm I.D.) packed with amide-80 silica beads (5 microns diameter). For post-column elution in the chemiluminescence system, 1 mM bis[2-(3,6,9-trioxadecanyloxycarbonyl)-4-nitrophenyl]oxalate and 3mM hydrogen peroxide in acetonitrile were used. The detection limit of each glycosaminoglycan was 100 fmol. The method was applicable to the determination of the levels of hyaluronic acid, chondroitin sulphate and dermatan sulphate in rat peritoneal mast cells.     

Oxidation of sulphides with alkaline potassium permanganate

Summary Sulphides are oxidised with potassium permanganate in alkaline medium to give dithionate. A method based upon this reaction is proposed for the determination of sulphides. The method consists in mixing the sulphide solution with an excess of permanganate in presence 1–2 M NaOH and 0.2 g telluric acid. The excess permanganate is then treated with ferrous ammonium sulphate in acid medium and the excess ferrous titrated with permanganate.     

Determination of sodium sulphate, calcium chloride and sodium chloride in gypsum plaster

Summary It has been shown that chloranilic acid and its salts can be used to determine sodium sulphate in the presence of calcium sulphate, calcium chloride in the presence of calcium sulphate, and sodium chloride in the presence of calcium chloride. The analysis is direct, the separation from non-desired components being carried out at the same time as the determination itself.One aspect of the use of chloranilic acid should be stressed, namely, that it sometimes is possible to differentiate between two salts that have the same anion but different cations, and examples have been given in this paper.     

Inhibition of copper corrosion in acidic sulphate media by eco-friendly amino acid compound

This investigation aimed to study a “green” non-toxic biodegradable copper corrosion inhibitor in an acidic sodium sulphate solution. The methods used in the investigation of cysteine as a copper corrosion inhibitor in an acidic sodium sulphate solution were: potentiodynamic measurements, open circuit potential measurements, and chronoamperometric measurements. Optical microscopy was used in addition to electrochemical methods. Potentiodynamic measurements show that cysteine has good inhibitory properties in an acidic medium. Polarisation curves indicate that the presence of cysteine in a sulphate solution decreases the current density and that using various cysteine concentrations results in the formation of a protective film on the surface of the electrode due to the formation of the Cu(I)-cys complex. These results are confirmed by chronoamperometric measurements. Furthermore, it is clear from microphotographs that a protective film does form on copper electrode in the presence of cysteine. The Langmuir adsorption isotherm indicates that cysteine is chemisorbed on the surface of the electrode.     

Studies in oxidation-reduction reactions: Oxidation with chloramine-b,iodine monochloride method

Chloramine-B has been used as an oxidizing agent in hydrochloric acid medium for the volumetric estimations of potassium iodide, arsenious oxide, tartar-emetic, mercurous chloride, stannous chloride, potassium thiocyanate, ferrous ammonium sulphate, hydrazine sulphate and hydroquinone, using iodine monochloride as a catalyst and pre-oxidizer. Chloroform is used as an indicator. It is coloured pink owing to the liberation of iodine during the titration and becomes light pale yellow at the end-point because of the formation of iodine monochloride.     

Volumetric studies in oxidation-reduction reactions : Oxidation with sodium hypochlorite iodine monochloride method

Alkaline sodium hypochlorite was used as an oxidant to determine arsenious oxide, hydrazine sulphate, ferrous ammonium sulphate, stannous chloride, sodium sulphite, potassium iodide, mercurous chloride, thallous chloride and tartar emetic, by a volumetric method, using iodine monochloride as catalyst and preoxidizer. During these titrations, the normality of the solution with respect to hydrochloric acid was kept between 5N and 7N, Chloroform was used as an indicator. Its pink colour due to the liberation of iodine during the titration turns very pale yellow at the end-point because of the formation of iodine monochloride     

Analytical applications of the photochemical action of light: Determination of ferric iron by photochemical reduction in the presence of citric and mandelic acids

A new method has been developed for the determination of ferric sulphate through its photochemical reduction with citric and mandelic acids in sunlight. The method consists in irradiating with sunlight a measured volume of the ferric sulphate solution together with an excess of citric or mandelic acid in a quartz or pyrex glass beaker until reduction is complete. The ferrous salt formed is determined by titration with a standard solution of sodium vanadate in the presence of the proper concentration of sulphuric and phosphoric acids, employing diphenylbenzidine or diphenylamine sulphonate as internal indicators. The photoreduction is greatly retarded by sulphuric acid.     

Titration of oxalic acid with cerium sulphate at room temperature using ferroïn as internal indicator

Evidence is presented to show that, contrary to the statements of earlier workers, the reaction between ceric sulphate and oxalic acid is quite rapid in hydrochloric acid medium specially in the presence of iodine monochloride as catalyst. We have now found that the need for a temperature of 50° in the cerimetric titration of oxalic acid using ferroïn as indicator is not due to the sluggishness of the reaction between oxalic acid and Ce^IV (as believed by Willard and Young) but because of the slow reaction between oxidised ferroïn and oxalic acid in the presence of sulphate ion derived from eerie sulphate. Conditions have now been developed for the titration of oxalic acid with eerie sulphate at room temperature in lN hydrochloric acid medium using ferroïn as indicator, and barium ion as scavenger for sulphate ion, which latter markedly retards the reaction between oxalic acid and oxidised ferroïn, as well as that between oxalic acid and Ce^IV. The method now developed has several advantages over that prescribed by Willard and Young because it avoids the high temperature of 50°, where the ferroïn indicator is found to undergo some dissociation. It also avoids the use of the iodine monochloride catalyst.     

The spectrophotometric determination of sulphate after its extraction with methyltricaprylammonium chloride into cyclohexane

Improvements are described to Flynn's procedure for the extraction of sulphate with Aliquat-336 and its subsequent determination as sulphuric acid. A single-point photometric measurement with sodium 2,4-dinitrophenate is applied to the determination of sulphate (ca. 10 mg kg^?1) in soils, and also in sulphur in organic compounds after oxygen flask combustion.