Détermination de l'ion chlorhydrique dans de l'eau condensée

The titration of chloride with Hg⁺² according to CLARKE allows the determination of lower concentrations as was possible according to MOHR. The greater sharpness of the endpoint at lower concentrations and the use of a more dilute Hg+2 solution permit a further lowering of the concentration limit down to 0.05 mg Cl^-/l, when using a calibration curve, the remarkable form of which perhaps may be attributed to the formation of HgCl₂.2HgO. This sensibility allows a suitable chloride determination in boiler condensates and the wetness determination of steam.     

Dosage complexométrique de bromures et d'iodures en présence l'un de l'autre

Bromides and iodides are determined simultaneously by precipitation as silver halide In another aliquot, silver halides are oxidized, bromine being liberated, the iodate formed is then reduced to iodide which precipitates. The silver precipitates are treated with ammoniacal tetracyano nickelate and displaced nickel is determined complexometrically Bromide is determined by difference     

Principes de l'iodimétrie absorptiométrique

A general method for the determination of oxidising or reducing agents has been investigated It is based on the measurement of the absorption of the spectrum of the 1₃^- complex Oxidizing agents may be determined by thu oxidation of iodide into I₃^-, reducing agents by reduction of I₃^-For a right application of this method one must have (a) all the iodine present in the state of 1₃^-, (b) the iodine produced by autoxidation of the iodide ion in negligible quantity Theconstants of the chief equilibria in which 13- is involved (equilibrium with I₂,I_2Br-,I₂Cl^-, IOH) and the kinetics of the autoxidation of the iodide ion in the presence and the absence of the catalyst Cu⁺² have been reinvestigated The acquned information enabled us to determine the general conditions of Applicability of this method and the realization of special analyses, The limit of detection by this method is 2.10^-7 gram equivalent of oxidizing or reducing agent per liter when absorptions are measured through a 5 cm layer.     

Dosage acidimétrique de l'ion aluminium

Acid titration of aluminium salts consists of two stages.1. Titration of the free acid. Complex ions are formed of aluminium with oxalatē of hydrofluorideions. 'I'he precipitation of aluminium hydroxide is retaided. Consequently the neutralisatiom of the free acid by the base is quite clear.2. Simultaneous titration of the acid and the aluminium ions. The solution with NaOH is neutralised until all the aluminium hydroxide is just precipitated. To avoid errors due to the formation of adsorption compounds, an excess of base is added and back-titrated with hydrochloric acid at the boiling point.These two titrations permit the determination of XXX acid and the aluminium content of the solution to approximately 0,3%.The influence of disturbing ions is studied.     

Oxydation électrochimique de l'ion thiocyanique. Application aux dosages et ä l'étude des réactions

The author has examined the rate of reaction of the system thiocyan ate/sulphate and cyanide, by means of the current/anode potential curves obtained during the electrolytic oxidation of thiocyanate in an acid medium.Corresponding with the minimum current detectable under our experimental conditions, we find a potential which agrees well with that determined by a classical potentiométrie method, and checked chemically. Consequently, it can be used to predict the chemical reactions taking place.From these curves, the relation between the anodic potential, the intensity of the electrolytic current, and the activity of the SCN^- ions has been deduced. These methods have been applied in a new method of investigating reactions in solution, viz. the potentiometry at constant current other than zero.     

Contribution á l'étude de la séparation des terres rares de fission par l'acide éthylènediaminetétraacétique

In the present paper, the authors investigate the conditions for a rapid and if possible analytical separation of a mixture Y-Eu-Pm-Ce for quantities of a few milligrams.Elution curves are given in function of the pH, which is the main influencing factor.A separation at pH 3.05 gives the best results.     

Généralisation de la méthode d'analyse de thorpe et application au dosage de l'isomère y dans l'hexachlorcyclohexane technique

The author presents a generalization of THORPE'S method for the analysis of complex mixtures and describes an application of it to the determination of the γ-isomer in technical hexachlorcyclohexane. This method has the advantage of not requiring expensive apparatus.Portions of the materials under examination are treated with CH₃OH at 20° C in such a way as to obtain, on the one hand, a solution saturated with regard to the (α + β ) isomers and, on the other hand, a solution saturated with regard to the (α + β + γ) isomers. Having determined tlie amounts of the products dissolved inthese solutions, the solubilities in CH₃OH enable the contents of the (α + β) and the γ-isomers to be calculated.     

Application de la diphényl-acroléine à l'analyse fonctionnelle

In highly acid alcoholic medium, diphenyl-acrolein develops a red colour with m-diphenols, in the cold. This reaction, which makes it possible to carry out determinations, has a sensitivity of one μg. Under the same conditions, yellow colouring is obtained with methylenes in the α position of a carboxyl or with primary aromatic amino groups. Various condensation products have been isolated.     

Sur le dosage argentométrique de l'anion phosphorique

1. In aqueous solutions of phosphoric acid or alcali phosphates, the PO₄^-3can be determined by potentiometric titraition with silver nitrate PO₄^-3 + 3 Ag⁺ ár unAg₃PO₄↓The pH value of the solution is maintained about 9 by using borax-buffer 2 The determination of phosphate ion is also possible by precipitation of Ag₃PO₄ with an excess of silver nitrate, the pH of the solution is adjusted between 7 and 8 by using a new buffer mixture containing NH₄⁺, NHXXX, and Ag⁺. After diluting the solution up to a known volume and filtering through dry filter paper, the excess of silver is determined by potentiometric titration with potassium bromide. This method gives very good results, it is applicable in the presence of Mg⁺² and Ca⁺². The presence of Fe⁺³ and Al⁺³ hinders the determination of the phosphate ion. 3. The properties of the ,,ammonium-silverdiamme” buffer system are described. This buffer contains NH₄⁺, NH₃ and Ag⁺ (the latter in excess with regard to NH₃)     

Dosage spectrophotométrique du molybdène par l'o-phénanthroline

Under certain conditions, o-phenanthroline and its derivatives, as well as 2,2',2′-terpyridyl, form relatively unstable red complexes with molybdenum(Vl) in presence of molybdenum(V). o-Phenanthroline is most sensitive, the molecular extinction coefficient being 6,290 at the absorption maximum (508 mμ). Beer's law is valid for the range 2–9 μg Mo/ml.     

Contribution à l'étude des méthodes de dosages électrotitrimétriques

The author establishes a general equation for the polarisation curve of an oxidation-reduction system taking into account the kinetics of reactions and concentration polarisation, and shows how it can be applied to the interpretation of titration curves obtained by the dead-stop end-point method of Foulk and Bawden and by the derivative method of Reilley, Cooke and Furman.     

Sur la réaction colorimétrique de l'aluminium avec la quinalizarine

The reaction between aluminium and quinalizarin has been studied, and some modifications have been made to the analytical procedure usually followed.The absorption curve of the Al-quinalizarin compound and that of quinalizarin alone have been drawn. We applied the continuous variations method in order to determine the structure and composition of the reaction product. The spectrophotometric readings have shown that the constituents of the coloured compound are bound in a definite ratio. 2:3.     

Dosage colorimétrique de l'uranium par le dibenzõylméthane

A colorimetric method for the determination of uranium by means of dibenzoylmcthane lias been studied and described.The complex is formed in aqueous pyridine in the presence of EDTA and tartaric acid; the optical density is measured at 415 mμ.Beer's Law applies; the sensitivity amounts to 0.005% uranium in the mineral.The method involves only one filtration and can be used in the presence of various impurities including Mo, W, V, Ge, Th, F and P.With a uranium content of more than 5% no single clement disturbs the determination. With a content of less than 0.5% the absolute error amounts to more than 0.01% only in the presence of 1% gold, 2% platinum or 10%, soluble strontium.The method described has been applied with completely satisfactory results to the analysis of pitchblende, antunite, thorianite, columbite, urano-thorianite, tantalite and carnotite containing from 0.05 to 25% uranium.     

Dosage colorimétrique de faibles quantités de cérium dans l'uranium

After extraction of the iron and uranium thiocyanates by ethyl acetate, the solution is oxidised by ammonium persulphate (in the presence of silver nitrate). The absorption of this solution is measured at 360 mμ by comparison with that of an aliquot previously reduced with oxalic acid, which selectively reduces cerium and manganese to the low valences. The absorption of manganese is deduced from a measurement at 525 mμ. By this method I to 5γ/ml cerium can be determined with an error of less than 15%.     

Dosage colorimétrique du cuivre dans les aciers par l'acide rubéanique

The rapid colorimetric determination of copper has been studied by means of the coloured reactions of copper salts with dithio-oxamide or rubeanic acid. This method can be used for the determination of copper, contained in an impure state in steels, in the presence of iron and some alloy elements without first extracting in an acetic buffer medium, the iron being made complex by citric acid. The method can equally be applied to the determination of small quantities of copper in different metals and alloys. The accuracy obtained is about ± 2.5 % of the quantity of copper.     

Détermination des constantes de stabilité des complexes de tl+ avec l'acide ethylénediaminotétracétique (edta) et avec l'acide nitrilotriacétique (nta)

The range of stability of the thallium complex with etylenediaminetetraacetic acid (EDTA) and with ammoniatriacetic acid (NTA) has been determined. In the presence of an excess (100 x ) of chelating agent, the formation of the complexes starts at pH = 6 Chelation of the metal with EDTA is practically complete at pH = 7, while completion of the chelation with NTA is reached merely at pH = 9.The cathodic reduction of thallium(I) at the dropping mercury electrode is reversible as well for the chelated metal as for free TI⁺ ions.The shift of the polarographic half wave potential of Tl+ by addition of the chelating agents was used for the calculation of the stability constants of the chelates The following values have been found: K^c(EDTA) = 10^{-5.81 ± 0.05} (25°C. μ = ± 1.0) between pH = 7 and pH = 10.5. K^c(NTA) = 10^{-3.44 ± 0.03} (25°C. μ = ± 1.4) between pH = 9 and pH = 10.5.     

Séparation des isoméres de l'hexachlorocyclohexane par chromatographie en phase gaz

Hexachlorocyclohexane isomers can be separated by a glass bead technique with polypropylene glycol Niax 1025 as the stationary phase. The principal isomers separated are the γ-hexachloro-cyclohexane (Lindane isomer), the α, β, ε, and δ isomers and γ-heptachlorocyclohexane. The life of the glass bead column is short — about 20 days in constant use. A longer column life can be obtained by pretreatment of the glass beads.