Direct and Indirect Spectrophotometric Methods for Determination of Metronidazole in Pharmaceutical Formulations

Document Type : Original Article


Chemistry Dept./ College of Education for pure science, University of Tikrit, Iraq


pure form and in its pharmaceutical preparations. The first method (Direct), depend on Diazotization Coupling Reaction, includes the reduction of Metronidazole with Iron metal and hydrochloric acid followed reaction with Sodium nitrite and coupling reaction between the drug and 4-Aminoacetophenone, in a basic intermediate to form (pink-red) product, with the highest absorption at the wavelength 510 nm. The second method (Indirect), depended on the Oxidation of Metronidazole in presence of acidic medium by a known excess of N-Bromosuccinimide and subsequent determination of unreacted oxidant by reacting it with (Phenosafranin dye) to form a (red) product, with the highest absorption at the wavelength 514 nm. Beer's law is obeyed at the concentrations range of (10-225) µg/ml and (5-200) µg/ml with a molar absorptivity (5.86×104 L/ and (7.27×104 L/ for 4-Aminoacetophenone and Phenosafranin dye respectively. The limit of detections (LOD) were found to be 7.9×10-4 µg/ml and 5.9×10-4 µg/ml respectively. The suggested method was prosperity implement to the estimation of "This drug" in pure form and in its pharmaceutical formulations.


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