A Sensitive Spectrophotometric Assay for Tinidazole and Metronidazole Using a Pd-C and Formic Acid Reduction System


Abstract: A simple, sensitive and rapid spectrophotometric method for the determination of tinidazole (TZ) and metronidazole (MZ) in pure as well as in dosage form is described. The method is based on the reduction of the nitro group of drugs using a novel and versatile reduction system comprising 10% Pd-C and formic acid. The resulting amine was then subjected to a condensation reaction with sodium 1,2-naphthaquinone-4-sulfonate (NQS) to form red Schiff base with an absorption maximum at 510 nm. Beer's law was obeyed in the concentration ranges 2.0 to 45.0 \mu g mL^{-1} and 1.5 to 37.0 \mu g mL^{-1} with a limit of detection (LOD) of 0.44 \mu g mL^{-1} and 0.36 \mu g mL^{-1} for TZ and MZ, respectively. Other statistical analyses such as Student's t test and F test values are included. The sensitivity of the method surpasses that of the reported spectrophotometric methods. The method was successfully applied for the assay of different tablets, suspensions and injections of TZ and MZ.

Keywords: Spectrophotometry, Tinidazole, Metronidazole, Pharmaceutical formulations

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