Herbert Weisz

Katalytisch-kinetische bestimmung von katalase, kupfer, molybdän und jodid mit hilfe eines biamperostaten

Zusammenfassung Biamperometrisch erfassbare Reaktionen konnen durch Verwendung eines Strom-Spannungs-Wandlers mit Hilfe der “Potentiostat”-Methode ausgewertet werden. Die durch Katalase katalysierte Zersetzung von Wasserstoffperoxid, die Kupfer-katalysierte Oxydation von Jodid mit Peroxidisulfat, die Molybdan(VI)-katalysierte Oxydation von Jodid mit Wasserstoffperoxid und die Jodid-katalysierte Oxydation von Arsen(III) mit Cer(IV) werden zur Illustration dieser Moglichkeit verwendet. Es werden die Katalysatoren Katalase, Kupfer, Molybdan-(VI) und Jodid sowie Azid als Inhibitor fur Katalase im p.p.b.-p.p.m.-Bereich bestimmt.

Catalytic-kinetic absorptiostat technique with the indigo carmine—hydrogen peroxide reaction as the indicator reaction

Abstract The absorptiostat method previously described is used for the catalytic-kinetic determination of sulphur compounds (sulphide, thioacetamide. thiourea and thiosulphate) in the micromolar range by means of their catalytic action for the indigo carmine—hydrogen peroxide indicator reaction. The thiosulphate catalyst is activated by iron(III) or aluminium(III); aluminium(III) is deactivated by fluoride. On this basis, iron(III) is determined in the ng range, and aluminium(III) and fluoride in the μg range.

Thermometric and conductometric observation of copper(ii)-catalyzed reactions in the catalytic-kinetic difference method : Determination of microgram amounts of copper(ii)

Abstract The course of reactions in the catalytic-kinetic difference method, previously described, can also be followed by conductometry and thermometry. The copper-catalyzed decomposition of hydrogen peroxide can be followed by thermometry, and the copper-catalyzed oxidation of thiosulfate with hydrogen peroxide by conductometry. Both reactions can be used for the determination of microgram amounts of copper(II).

A quotient method of evaluation for the catalytic-kinetic difference method

Abstract A new variant of the catalytic-kinetic difference method is presented.The course of a catalyzed reaction, which proceeds simultaneously in two mixtures containing different catalyst concentrations, is followed by photometry. The maximum of the difference in transmittance being measured is a function of the quotient of the catalyst concentrations in the two mixtures and is independent of the rate constant. With this method of evaluation, a single calibration graph suffices for the determination of two different catalysts activating the same reaction. The maximum of the difference in transmittance is independent of temperature. The reaction between cerium(IV) and arsenic(III) catalyzed by iodide or osmium serves as an example. Two further examples are mentioned.

A short survey of semiquantitative methods of analysis and some new contributions

Abstract The definition and use of non-sophisticated semiquantitative methods in analytical chemistry are described. The most important principles for such techniques are discussed: colorimetry, comparison of time, counting of portions, identification limit, area, temperature, volume of precipitate. Some new methods are proposed: strip methods with three different volumes or with three different reagents, an 8-channel colour comparator, titrations with and on impregnated paper, and an evaporation method. Examples are given for the estimation of various ions in the microgram or nanogram range.