采样极谱法测定SOD模型化合物催化超氧离子歧化反应速率常数

用采样极谱法研究了非质子溶剂中SOD模型化合物催化O₂^-的歧化反应,用简化的函数关系代替动力学微分方程的准确解.通过测定极限催化电流与极限扩散电流比随SOD模型化学物浓度及滴汞电极滴下时间的变化,确定催化O₂^-歧化反应速率常数K₁.     

Electrochemical study and analytical applications for new biologically active 2-nitrophenylbenzimidazole derivatives

The present study addresses the electrochemical behavior and the analytical applications of six 2-nitrophenylbenzimidazole derivatives with activity against Trypanosoma cruzi. When studied in a wide range of pH, by differential pulse polarography, tast polarography and cyclic voltammetry, these compounds exhibited two irreversible cathodic responses. With analytical purposes, the differential pulse polarography mode was selected, which exhibited adequate analytical parameters of repeatability, reproducibility and selectivity. The percentage of recovery was in all cases over 99%, and the detection and quantitation limits were at the level of 1 × 10⁻⁷ mol L⁻¹ and 1 × 10⁻⁶ mol L⁻¹, respectively. In addition, the differential pulse polarography method was successfully applied to study the hydrolytic degradation kinetic of one of the tested compounds. Activation energy, kinetic rate constants at different temperatures and half-life values of such application are reported.     

Polarographic studies on the hydroxamic acid complexes

Summary The Molybdenum complex of benzohydroxamic acid is completely extracted with a chloroform solution of 2-aminoethanol. The extract when subjected to d.c. and Tast polarography after mixing with appropriate volumes of aqueous acetic acid and methanolic lithium chloride furnish a well-defined reduction wave which can be utilised for the determination of the metal. The method is sensitive and highly selective. Different parameters like acids, and solvents have been studied and the nature of the electrode process has been discussed. The metal can be determined in presence of a host of foreign ions and the method can be applied to determine traces of molybdenum in steel (rel. standard deviation ±1.19%).

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Polarographische Untersuchung von HydroxamsäurekomplexenI. Gleichstrom- und Tastpolarographische Bestimmung von Mikromengen Molybdän nach Extraktion des Benzohydroxamsäure-Komplexes

Zusammenfassung Der Molybdänkomplex der Benzohydroxamsäure läßt sich mit einer Lösung von 2-Aminoethanol in Chloroform vollständig extrahieren. Die Gleichstrom- oder Tastpolarographie des Extraktes (nach Zugabe von Essigsäure und methanolischer Lithiumchloridlösung) ergibt eine gut ausgebildete Reduktionsstufe, die zur Bestimmung benutzt werden kann. Das Verfahren ist empfindlich und hochselektiv. Verschiedene Parameter, wie Säurezusatz und Lösungsmittel, wurden untersucht und die Art des Elektrodenvorgangs wird diskutiert. Molybdän kann in Gegenwart zahlreicher Fremdionen bestimmt werden. Die Anwendung zur Stahlanalyse wird beschrieben (rel. Standardabweichung ±1,19%).

Dedicated to Prof. Dr. Fritz Umland on the occasion of his 60th birthday