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1.
Habibollah Eskandari Gholam Hassan Imanzadeh Karkaragh Ali Ghanbari Saghseloo Ghadamali Bagherian Dehaghi 《Analytical sciences》2004,20(8):1227-1230
The formed cobalt-a-benzilmonoxime complex was adsorbed onto microcrystalline naphthalene. Then it was determined by zero and first derivative spectrophotometry and by atomic absorption spectrophotometry (AAS) after dissolving into chloroform and methylisobutylketone (MIBK), respectively. Under optimum conditions, cobalt in the range of 1.0 - 20.0, 0.4 - 30.0 and 2.5 - 50.0 microg could be determined by spectrophotometry, first derivative spectrophotometry and AAS method, respectively. By the method, a preconcentration factor equal to approximately 30 for cobalt was obtained. The effect of diverse ions on the determination of 5.0 microg cobalt was also studied. The method was successfully applied to some pharmaceuticals and synthetic alloy samples. 相似文献
2.
3.
T. V. Ramakrishnan H. R. Krishnamurthy S. R. Hassan G. Venketeswara Pai 《Journal of Chemical Sciences》2003,115(5-6):767-774
Manganites of the LA1−x
Ca
x
MnO3 family show a variety of new and poorly understood electronic, magnetic and structural effects. Here we outline a new approach
recently proposed by us, where we argue that due to strong Jahn-Teller (JT) coupling with phonons the twofold degeneratee
g
states at the Mn sites dynamically reorganize themselves into localised, JT polaronsl with exponentially small inter-site hopping, and band-like, nonpolaronic statesb, leading to anew 2-band model for manganites which includes strong Coulomb and Hund’s couplings. We also discuss some results from a dynamical mean-field theory treatment
of the model which explains quantitatively a wide variety of experimental results, including insulator-metal transitions and
CMR, in terms of the influence of physical conditions on the relative energies and occupation of thel andb states. We argue that this microscopic coexistence of the two types of electronic states, and their relative occupation and
spatial correlation is the key to manganite physics.
Dedicated to Professor C N R Rao on his 70th birthday 相似文献
4.
Saad S. M. Hassan 《Mikrochimica acta》1974,62(1):51-57
Summary A new micromethod for spectrophotometric determination of hydrazine compounds is described. It is based on a reaction withperi-naphthindan-2,3,4-trione hydrate at pH 2.5 to give a red precipitate of dihydroxy-peri-naphthindenone which is dissolved in methanol and measured at 460 nm. The results obtained show an average recovery of 99.8 %, the precision being ± 1 %.
Zusammenfassung Eine neue Mikromethode zur spektrophotometrischen Bestimmung von Hydrazinverbindungen wurde beschrieben. Sie beruht auf der Reaktion mit peri-Naphthindan-2,3,4-trion-hydrat bei pH 2,5, wobei ein roter Niederschlag von Dihydroxy-peri-naphthindenon entsteht, der in Methanol gelöst und bei 460 nm gemessen wird. 99,8% Substanz werden wiedergefunden, die Genauigkeit beträgt ±1%.相似文献
5.
The effects of acidity, fluoride concentration, temperature and concentration of manganese in the reaction between KMnO(4) and Mn(II) were studied potentiometrically. The rate of reaction is increased by increasing the fluoride concentration and/or decreasing the acidity of the solution. The formal redox potentials of the MnO(-)(4)/Mn(III) and the Mn(III)/Mn(II) systems were determined at different pH values. The E degrees values obtained by extrapolation to pH = 0 were 1.58 and 1.52 V respectively. The amount of Mn(II) determined was varied from 5 to 56 mg. The net reaction can be represented as MnO(-)(4) + 10HF(-)(2) + 4Mn(2+) right harpoon over left harpoon 5MnF(-)(4) + 2H(+) + 4H(2)O. 相似文献
6.
Up to 100 microg of sample can be collected from gold or silver alloys by rubbing the specimen with the ground hemispherical tip of a 4-mm Pyrex glass rod. Gold alloys are then dissolved in potassium cyanide solution containing hydrogen peroxide; silver alloys are exposed to vapours of nitric acid. Procedures for transfer, ring oven separation and identification of alloy constituents in the sample solutions are described. 相似文献
7.
Saad S. M. Hassan 《Fresenius' Journal of Analytical Chemistry》1973,266(4):272-274
Summary The solid state ion-selective chloride and bromide electrodes are used for the microdetermination of chlorine and bromine in organic compounds. After combustion in an oxygen-filled flask, potentiometric titration with silver nitrate at pH 5–7 in presence of 50% dioxan is carried out. Results accurate to ±0.3% absolute are obtained with some partially and highly halogenated compounds.
Mikrobestimmung von Chlor und Brom in einigen organischen Verbindungen mit Hilfe von ionenselektiven Elektroden
Zusammenfassung Chlorid- und bromidselektive Festkörperelektroden wurden zur Chlor- und Brombestimmung in teilweise bzw. hochhalogenierten organischen Verbindungen benutzt. Nach Verbrennung im Sauerstoffkolben erfolgt eine potentiometrische Titration mit Silbernitrat bei pH 5–7 in Gegenwart von 50% Dioxan. Die erhaltenen Ergebnisse sind auf ±0,3 % genau.相似文献
8.
Synergistic extraction of samarium with TTA(HA) and TPPO or TOPO (B) mixtures were investigated. The extracted complex was proved to have the general formula SmA3 · 2B. A graphical determination for the formation constants of these complexes gave the values 3.9 × 1013 and 8.2 × 1010 for SmA3 · 2TOPO and SmA3 · 2TPPO in benzene, respectively. 相似文献
9.
10.
Summary A new simple, rapid and accurate amplification micro method for fluoride determination is described. It is based on the reaction between the sparingly soluble calcium iodate and the fluoride ion. After adding isopropyl alcohol to the solution, so that its final concentration is 65%, and filtering, an equivalent amount of the iodate is obtained. The latter is titrated iodometrically resulting in a six-fold amplification of the titre. The method is reproducible over a range from 0.4–8 mg fluoride ion. The mean recovery is 99.69%, after applying a correction factor due to potassium iodate solubility.
Zusammenfassung Ein Multiplikationsverfahren zur Mikrobestimmung von Fluorid wurde beschrieben. Es beruht auf der Umsetzung zwischen dem schlecht löslichen Calciumjodat und Fluorid. Nach Zusatz von i-Propylalkohol, bis die Lösung 65% davon enthält, wird filtriert. Die äquivalente Jodatmenge wird jodometrisch titriert. Zwischen 0,4 und 8 mg Fluorid sind die Ergebnisse reproduzierbar. Bei Anwendung eines Korrekturfaktors wegen der Löslichkeit von Kaliumjodat wurden 99,69% Fluorid wieder gefunden.相似文献