D. Monnier

Study of the behaviour of solid-state membrane electrodes : Part I. Role of various factors on the limits of sensitivity of chloride and fluoride electrodes

Abstract A study of the behaviour of the chloride-selective electrode in the concentration range below the linear response region, has shown that the nonlinearity is principally due to three factors: the solubility of the membrane, the concentration of chloride impurities and the interference of ions of the background electrolyte or other impurities. Similar studies with fluoride electrodes have shown that, in addition to these factors, other parameters also play an important role.

Analytical study of two diazotization-coupling reactions : Application to the determination of nano-amounts of nitrite in water

Abstract Three spectrophotometric methods for the determination of nitrite have been developed based on diazotization of 4-aminoacetophenone followed by coupling with N-phenyl-1-naphthylamine or N-phenyl-2-naphthylamine. In the former case, the coloured species shows an absorption maximum which depends on pH; the dissociation constants were established for a (1 + 1) water-ethanol system: K 1 = 2·10 -14 and K 2 = 10 -2 . The anion of the coloured species has a molar absorptivity of 89000 at 618 nm and traces of nitrite of the order of 1 ng ml -1 (dilution factor 3.57) can be determined. The cationic form AH + 2 present in strongly acidic media has a molar absorptivity of 49000 at 568 nm. The absorbing species formed with N-phenyl-2-naphthylamine has a molar absorptivity of 18,300 at 524 nm, and the absorbance is independent of pH, probably because of intramolecular hydrogen bonding. The method has been applied to the determination of nitrite in natural waters.

Chronopotentiometric study of the oxidation of some diluted amalgams in the presence of traces of oxygen dissolved in aqueous solution: Part II: Study of the influence of various parameters on the reaction rate

Summary The behaviour of dilute amalgams in the presence of trace amounts of dissolved oxygen in aqueous solution has been studied. The diffusion of oxygen in the solution and that of metal in the amalgam seem to be the factors which determine the rates of oxidation of Zn, Cd, Pb and Tl amalgams. The variation of metal concentration in a drop of amalgam with time of contact with traces of dissolved oxygen has been treated mathematically. The influence of different parameters was studied experimentally and these are in accordance with the proposed equation. A simple relation between the rate of oxidation and the amount of oxygen in the solution was found and this can be used for the determination of traces of oxygen in solution.

Errors in the gran addition method: Experimental determination of errors by means of a fluoride-selective electrode

The errors incurred in the Gran addition technique have been experimentally determined with a fluoride-selective electrode. The results obtained agreed with the theory proposed in the previous Parts. To obtain maximal precision, the following conditions must be satisfied: (a) the concentration of the standard solution should be as close as possible to that of the unknown solution; (b) the electrode slope, k, must be determined with utmost precision ; and (c) 1

Contribution to the study of an inorganic semi-quantitative method of analysis: analysis of chromium and nickel

Abstract The authors propose a new semi-quantitative; method of analysis,simple and very rapid, based on the use of sensitive and specific organic reagents, by determination of the limit of detection of the reaction. Two methods are described. 1. Determination of chromium by use of the following reagents: gum guaiacum, strychnine or diphenylcarbazide. 2. Determination of nickel by means of cyclohexanedionedioxime, rubeanic acid or diammonium tetrathiocyanatomerculate.

Un dosage polarographique et colorimétrique de la tyrosine

Abstract A simple and rapid method of determining tyrosine by polarography, after nitration with 0.15 N nitric acid, is proposed. The results are satisfactory. The low limit of tyrosine that can be determined is 20 g. The method is impeded by considerable quantities of certain amino acids and by a large number of organic sulphur derivatives. The error for quantities of tyrosine between 0.1 g/l and 0.3 g/l is less than 2%. Colorimetric determination of the same solution gives results appreciably similar to those obtained by polarography, but the method is less selective.

Determination of trace amounts of silver(I) by polarographic. anodic stripping and chronopotentiometric methods at a mercury electrode: Studies in aqueous and nonaqueous media

Abstract The determination of trace amounts of silver by voltammetry at a mercury electrode is described. The choice or conditions for obtaining separate reduction or oxidation signals for silver(I) and mercury is discussed. Theoretical and experimental studies showed that in aqueous medium none of the complexing agents tested provides separation of the silver(I) and mercury waves. When acetonitrile is used as solvent, silver can be determined at a mercury electrode without preconcentration, by d.c. polarography, anodic stripping voltammetry and anodic stripping chronopotentiometry with sensitivities as low as 5· 10 -5 M , 5 · 10 -7 M and 10 -8 M , respectively. It was confirmed that in acetonitrile medium. Ag(I)/Ag(Hg) behaves reversibly in the first two methods.

Macro- et microdosage de traces de cobalt dosages spectrophotométrique et polarographique du cobalt dans les aciers ma 2 B, edelweiss

Resume Il est propose une methode de dosage spectrophotometrique permettant de determiner la concentration de cobalt dans un acier 18/8, sur 0.1 a 0.5 g pour le macrodosage et sur 1 mg pour le microdosage; les erreurs sont comprises entre 4 et 6%. La methode consiste a extraire le fer, a separer le cobalt sur resine Dowex I–X 8 et a determiner la densite optique du complexe cobaltnitroso-sel R. La limite de sensibilite du dosage est de 0.01 μg/ml. Le microdosage se fait en microcuve avec un photomultiplicateur; il permet de doser encore 0.005 μg de cobalt. Il est aussi propose une methode polarographique moins sensible (0.5 μg/ml) mais plus rapide. Les erreurs sont du meme ordre de grandeur.

Dosage du cobalt dans les aciers 188 base sur la formation du 60mco par activation aux neutrons thermiques

A method for the determination of cobalt in 188 steels, based on formation of 60mCo is proposed. Most of the iron is extracted, then cobalt is extracted as its α-nitroso-β-naphthol complex into toluene. The losses are determined exactly. A determination is complete within 2 h with a precision of ±9% ; the limit of sensitivity is 2 μg of cobalt. The results obtained (average 350 p.p.m.) are compared with results obtained spectrophotometrically (average 368 p.p.m.).