Acid-base titrations in nonaqueous solvents Analysis of dimethyl sulphate

A nonaqueous titrimetric procedure was developed for the determination of the dimethyl sulphate, methyl hydrogen sulphate and sulphuric acid content of dimethyl sulphate samples. Methyl hydrogen sulphate and sulphuric acid are determined by a differentiating potentiometric titration in pyridine with tributylethylammonium hydroxide. Pyridine converts the dimethyl sulphate into the weakly acidic methylpyridinium methyl sulphate which does not interfere in the titration. Dimethyl sulphate is determined by reacting it with an excess of 2-dimethylaminoethanol and titrating the excess with perchloric acid. Precision and recovery data for commercial samples of dimethyl sulphate are presented.     

Thermogravimetric study of the reduction of basic lead sulphate

In this paper, the results of the study of the reduction of basic lead sulphate with a gas (CO + CO₂) mixture are presented. This is a secondary reaction during the reduction of lead sulphate. The change in the both lead and PbS content in the reaction products, depending on the process temperature and the composition of the gaseous phase, was established. The comparison of the rate of the reduction reaction of lead sulphate and basic lead sulphate shows that the process proceeding with a higher output is the reduction of basic lead sulphate.     

Determination of inorganic sulphate in plasma by reversed-phase chromatography using ultraviolet detection and its application to plasma samples of patients receiving different types of haemodialysis

The determination of sulphate in plasma is described, making use of reversed-phase high-performance liquid chromatography with ultraviolet detection. The concentration of inorganic sulphate determined in plasma of twenty healthy volunteers was 0.307 +/- 0.092 mmol/l (mean +/- S.D.). In one stable chronic dialysis patient the kinetics of plasma sulphate removal were monitored during and after one single pass dialysis. In addition, plasma sulphate concentrations were determined in three stable chronic dialysis patients during a consecutive scheme of two single pass dialyses, five Redy dialyses and three single pass dialyses. As expected, plasma sulphate accumulates in plasma to a high steady-state level under Redy dialysis, whereas during single pass dialysis sulphate is efficiently removed.     

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.     

Complexometric estimation of ferric iron

Summary Ferric iron has been determined alone or in presence of barium chloride, calcium chloride, magnesium sulphate, mercuric chloride, manganese sulphate, strontium nitrate, chromic sulphate or zinc sulphate by titrating it with EDTA, using potassium thiocyanate-p-anisidine indicator. In these complexometric titrations, the quantitative results obtained by using potassium thiocyanate-p-anisidinie indicator are comparable with those obtained with Bindschedler's green indicator; and the metallic salts mentioned above do not interfere in the estimation of ferric iron by this method.     

Differential pulse polarographic study of the hydrolysis of endosulfan and endosulfan sulphate in emulsified medium. Application to the determination of binary mixtures of organochlorine pesticides

Hydrolysis reactions of endosulfan and endosulfan sulphate in the emulsified medium formed with ethyl acetate and a mixture of the two surfactants Hyamine 2389 and Triton X-405 are studied by differential pulse polarography. Besides the heptachlor-endosulfan sulphate pair, whose peak potentials are sufficiently different at pH 8.0 to allow their simultaneous determination, the organochlorine pesticide binary mixtures endosulfan-endosulfan sulphate, dieldrin-endosulfan and dieldrin-endosulfan sulphate can be determined based on their hydrolysis reactions in basic medium and on their different reaction rates. The endosulfan-endosulfan sulphate pair can be determined by allowing the mixture to hydrolyse at pH 11.0 and measuring the endosulfandiol peak for the determination of endosulfan. The analysis of the mixture dieldrin-endosulfan is based on endosulfan hydrolysis at pH 12.0 in which dieldrin is not hydrolysed. Dieldrin and endosulfan sulphate can also be determined simultaneously in a 0.5M sodium hydroxide medium. When determining one pesticide in binary mixtures containing a 5.0 x 10(-6)M concentration of the other pesticide, the lower limits of the calibrations obtained were: endosulfan-endosulfan sulphate mixture, 4.0 x 10(-6) and 1.0 x 10(-6)M respectively; heptachlor-endosulfan sulphate mixture, 2.0 x 10(-6)M for endosulfan sulphate; all other cases, 3.0 x 10(-6)M.     

Oxidimetric methods for the volumetric estimation of sulphite

1. The use of permanganate, ceric sulphate, and dichromate for the estimation of sulphite has been reinvestigated, although these reagents have heen discarded as useless by earlier investigators. By using catalysts under controlled acid concentration, we have been able to develop conditions for the quantitative oxidation of sulphite to sulphate at room temperature by any one of these oxidizing agents, avoiding the formation of dithionate. Copper sulphate and iodine monochlonde have been found useful as catalysts with potassium permanganate and dichromate; but only iodine monochloride with ceric sulphate. 2. Sodium sulphite is also oxidized quantitatively to sulphate at room temperature, when added to excess of sodium vanadate solution containing 5 to 6N hydrochloric acid and iodine monochloride as catalyst.     

Volumetric Studies In Oxidation-Reduction Reactions: Oxidation with ceric sulphate ferrous ethylenediamine sulphate method

Ceric sulphate has been used as an oxidizing agent in acid medium for the indirect volumetric determinations of ferrous ammonium sulphate, cuprous chloride, potassium thiocyanate, sodium thiosulpliate, sodiuin nitrite, hydrogen peroxide, sodium oxalate, hydroquinone and pyruvic acid. The excess of ceric sulphate added to each of the substances in acid medium was titrated with standard ferrous ethylenediamine sulphate solution using ferroin as an indicator.     

Rapid decomposition of organic materials with acidic lithium sulphate flux containing catalysts, oxidizing agents or reducing agents, and Kjeldahl determination of nitrogen

Organic compounds and natural materials such as dimethylglyoxime, p-nitrophenol, alpha-nitroso-beta-naphthol, 4-(2-pyridylazo)-resorcinol, phenylhydrazine hydrochloride, monopyrazolone, residual fuel oil and coal can be rapidly decomposed in the melting state with various ratios of sulphuric acid-lithium sulphate (v/w) mixture containing catalysts, oxidizing agents or reducing agents such as elemental selenium powder, cupric sulphate, ceric sulphate and stannous sulphate. The quantitative recovery of nitrogen in the melting medium can be obtained with the Kjeldahl method.     

Any x-ray diffraction study on SO2−4-H2O interactions in the presence of nickel and magnesium ions

An x-ray diffraction study was made on solutions of sulphate anion with different cations. In all cases the sulphate ion was found to be hydrated. From at least-squares fitting program we obtained a number of between 7 and 8 water molecules interacting with each sulphate group. The hexa-aquo cations possess a second shell of water molecules.     

Indirect flame photometric determination of sulphate ions

In this paper the possibilities have been studied of determining sulphate ions by indirect flame photometry by difference. Barium and Strontium in constant concentration were used as background elements. By means of the methods proposed sulphate ions can be determinined in the concentration range 0 to 70 p.p.m. with barium and 0 to 110 p.p.m. with strontium. The determinations can be carried out in dilute solutions of alkali metal sulphates and sulphate ions can also be estimated in the presence of macroquantities of other compounds. This may prove useful for the quantitative estimation of sulphate as an impurity in Chemical reagents. Some examples are given of the determination of the degree of purity of substances containing sulphate as impurities.     

Some factors influencing the solubilities of amine sulphates

The relationship between the molecular structures of amines and the solubilities of their sulphates has been examined with the object of finding a better reagent than benzidine for the determination of sulphate. It has been established that the two aromatic rings must have a tendency to be coplanar and collinear, if the sulphate solubility is to be low. With the help of this theory, 4 : 4'-diaminotolane sulphate has been found to be less soluble than bcnzidine sulphate.     

The indirect spectrophotometric determination of the sulphate ion with 2-aminoperimidine

A new spectrophotometric determination of the sulphate ion is described which uses 2-aminoperimidine hydrochloride as a precipitating reagent. The excess of the reagent is measured at 305 nm. The procedure deals with sulphate in the range 4–120 p.p.m., and relies on simple calibration. The relative standard deviation for 50 p.p.m. of sulphate is 3.7%. The interference of 100 p.p.m. of phosphate, fluoride and nitrate is only slight in the determination of 50 p.p.m. of sulphate. The method is recommended for the determination of sulphate in rain and surface waters.     

Electrodeposition of actinides for alpha-spectrometry

The electrodeposition of the actinides U, Th, Pu, Am, and Cm on stainless steel disks was studied. A sodium hydrogen sulphate — sodium sulphate buffer 0.63M in total sulphate and a ratio sodium hydrogen sulphate to total sulphate ranging from 0.16 (pH 1.8) to 0.48 (pH 1.3) allows the quantitative electrodeposition of the given actinides. No actual pH measurement is needed. Moreover, sodium hydrogen sulphate is an excellent substrate for the wet ashing of organic matter prior to electrodeposition. The method is very robust.     

Development of a flow-sheet for the radiochemical processing of irradiated sulphate targets for the production of carrier-free 32P

Carrier-free ³²P was produced in KAlpakkam MINI reactor (KAMINI) via ³²S (n, p) ³²P using its small fast flux component. This method has established the flow-sheet for the production of ³²P from sulphate targets such as magnesium sulphate and strontium sulphate which can withstand high temperatures of fast reactors unlike the conventionally used sulphur powder. The chemical processing involved (i) struvite precipitation method for magnesium sulphate and (ii) co-precipitation with ferric hydroxide method for strontium sulphate.     

Enhanced capacity of chitosan for transition-metal ions in sulphate-sulphuric acid solutions

Batch measurements have shown that the collection yields of chitosan for chromium(III), iron(III), nickel, copper(II), zinc and mercury(II) from sulphuric acid solutions are higher when the solutions contain ammonium sulphate, or when chitosan conditioned in ammonium sulphate is used, particularly at pH 3.0 and 5.0. The contrary is verified for the oxy-anions vanadate, chromate and molybdate. Manganese is never collected. At pH 1.0 no collection occurs. A procedure for recycling chromatographic columns includes fixation of Cu or Ni from a sulphate solution at pH 3-5 on sulphate-conditioned chitosan, and elution with 0.1M sulphuric acid/0.1M ammonium sulphate at pH 1.0; the presence of sulphate in the eluent obviates the detrimental effect of sulphuric acid on the next cycle. Sulphate is the favoured counter-ion of the chelated cations and its action produces shorter chromatographic bands. The interaction of sulphate with chitosan is discussed in terms of crystallinity and steric distribution of the protonated amino-groups in the polymer. Data on the new diethylaminohydroxypropylcellulose are included.     

Liquid chromatographic assay for constituent disaccharides of hyaluronic acid and chondroitin sulphate isomers

An improved high-performance liquid chromatographic (HPLC) method for unsaturated disaccharides prepared from hyaluronic acid and various chondroitin sulphate and dermatan sulphate isomers was developed, which involves an ion-exchange resin prepared from a sulphonated styrene-divinylbenzene copolymer. The retention times of the individual unsaturated disaccharides were unique and reproducible, the disaccharides appearing in the following order: unsaturated non-sulphated disaccharide derived from hyaluronic acid, then unsaturated 6-sulphated, non-sulphated and 4-sulphated disaccharides from chondroitin sulphate isomers. Unsaturated disulphated disaccharide G had a much shorter retention time than the unsaturated non-sulphated disaccharide derived from hyaluronic acid. The contents of these individual unsaturated disaccharides could be determined with similar sensitivities on the basis of their ultraviolet absorbance. Selective and unique retention times and good resolutions were found for various unsaturated disulphated and trisulphated disaccharides. The proposed method can be used to determine various chondroitin sulphate and dermatan sulphate isomers in addition to hyaluronic acid in amounts as small as 100 ng to 8 micrograms. The practicality of this method was verified by its application to the separation and determination of the different types of chondroitin sulphate and dermatan sulphate isomers derived from human arteries in the presence of appreciable amounts of hyaluronic acid.     

Continuous potentiometric determination of sulphate in a differential flow system

Continuous monitoring of sulphate in a differential flow system equipped with two lead ion-selective electrodes is described. All solutions contained 75% methanol and were adjusted to pH 4. In the flow cell, a standard solution of lead(II) is pumped past the first sensing electrode and is mixed with the sample stream containing sulphate in a small mixing chamber; the mixture containing excess of lead(II) and lead sulphate precipitate then flows through the second sensing electrode chamber. The potential difference depends on the sulphate content in the sample. The effects of lead electrode passivation and the interferences of calcium and chloride are discussed. The system is useful for routine sulphate determination in the range 30–400 mg l^-1 with an accuracy of ±5%     

Viscometric studies on the interaction of sodium dodecyl sulphate with transfusion gelatin

Summary Interaction of sodium dodecyl sulphate with transfusion gelatin has been studied in low p_H range by viscosity measurements. It was found that with the addition of sodium dodecyl sulphate to transfusion gelatin at p_H's 2.0, 3.0 and 4.0 viscosity decreases until precipitation sets in. With further addition of sodium dodecyl sulphate precipitate redissolves. The decrease in viscosity is probably due to greater compactness of the protein molecules. The behaviour of isoelectric transfusion gelatin towards sodium dodecyl sulphate has been found to be markedly different.With 3 figures