Analytical Sciences

Determination of Streptomycin in a Pharmaceutical Sample Based on Its Degradation by Hydrogen Peroxide in the Presence of Copper(II)

Snezana S. MITIC,* Slavica M. SUNARIC,** and Snezana B. TOSIC*

*Faculty of Natural Sciences and Mathematics, Department of Chemistry, University of Nis, Visegradska 33, P. O. Box 224, 18000 Nis, Serbia and Montenegro
**Faculty of Medicine, Department of Pharmacy, University of Nis, Bulevar dr Zorana Djindjica 81, 18000 Nis, Serbia and Montenegro

The kinetics of streptomycin degradation by hydrogen peroxide at pH 7.4 was investigated. The reaction was catalyzed by traces of Cu(II) ions, and it was followed spectrophotometrically at 322 nm by applying the initial-rate method. The kinetic parameters of the reaction are reported, and a rate equation is suggested. From the dependence of the relative rate constants on the temperature, the activation energy was calculated to be 57.5 kJ/mol. Based on this reaction, a kinetic method for streptomycin determination is proposed. The calibration graph is linear in the ranges 1.94 - 15.48 µg/cm³ and 0.15 - 1.94 µg/cm³. The influence of foreign ions and molecules on the accuracy of the determinations was investigated. The proposed kinetic method has high selectivity and good sensitivity, and enabled to determine streptomycin in pharmaceutical samples.

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