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1.
The copper-catalyzed decomposition of hydrogen peroxide is retarded by cyanide. The oxidation of cyanide by hydrogen peroxide is likewise catalyzed by copper ions. The decomposition reaction of H2O2; can be followed thermometrically. Therefore, at a known copper concentration an unknown amount of cyanide can be determined from the retardation time; and an unknown amount of copper can be determined by adding a known amount of cyanide. Moreover, after the end of the retardation time, unknown copper concentrations can also be determined from the slope of the temperature curve (tana). Copper was determined in the range 4–40 μg, and cyanide in the ranges 3–30, 6–60 and 8–80 μg.  相似文献   

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Zusammenfassung Es wird eine Methode zur direkten jodometrischen Hydroxylaminbestimmung beschrieben, bei der die Titration in Anwesenheit von Magnesiumoxyd erfolgt. Die Methode ist schnell ausführbar, die Resultate sind ausreichend genau und lassen sich gut reproduzieren.  相似文献   

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A method is described for the amperometric titration of copper with thioacetamide (TAA) at pH 2-6, and at room temperature. Current is recorded with a potential in the range -0.25 to -0.40 V applied across a dropping mercury and calomel electrodes. The presence of Zn(2+), Tl(+), Pb(2+), Fe(2+), Co(2+) and Ni(2+), even in thousandfold excess, causes no interference. The reaction is rapid at room temperature, and the mean error lies between 1 and 2%.  相似文献   

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Biamperometrically observable reactions may be evaluated by the “potentiostat”-method with the application of a current-to-voltage transducer. The catalase-catalyzed autodecomposition of hydrogen peroxide, the copper-catalyzed oxidation of iodide with peroxydisulfate, the molybdenum(VI)-catalyzed oxidation of iodide with hydrogen peroxide, and the iodide-catalyzed oxidation of arsenic(III) with cerium(IV) are used to illustrate this concept. The catalysts, catalase, copper(II), molybdenum(VI) and iodide, as well as azide as an inhibitor for catalase, can be determined in the p.p.b.-p.p.m. range.  相似文献   

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A photometric method is proposed for the determination of cobalt in the form the nitroso-R-salt complex in 5–10 nil of blood serum. The organic matter is destroyed by mineral acids. Iron and copper are separated by oxine and dithizone; they can be determined later. Cobalt (just like traces of other elements), complexed by diethyldithiocarbamate and oxine, is extracted by chloroform and then determined in, the form of the nitroso-R-salt complex. The photometric measurement is carried out in a capillary cuvette 10 cm long and 0.7 ml volume, using a green Literatur S. 561. filter. Amounts of 0.02–0.3 g cobalt can be determined quantitatively, with an accuracy of ±5%.  相似文献   

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