Spectrophotometric method for determination of metronidazole in pure and tablet dosage forms via Schiff's base formation by coupling with crotonaldehyde

Abstract

Background: UV-visible spectrophotometric methods are popular because of their simplicity, accuracy, precision and low cost.

Objectives: In this study a new simple,accurate,economical and reproducible spectrophotometric method for the quantitative determination of metronidazole was developed and validated.

Methods: The method is based on the reduction of the nitro group in metronidazole with zinc powder under acidic condition (5N HCl)at 27°C in methanol for 15 minutes followed by coupling the resulting amine with crotonaldehyde to form a yellow chromogen with a λmax of 408nm.The proposed method was validated according to international conference on harmonization (ICH)guidelines and used to assay a sample of standard metronidazole powder and four different brands (A,B,Cand D)of metronidazole tablets.

Results: The assay results were validated by comparing with British pharmacopeia B.P method for assay of metronidazole.Beer's law was obeyed within a concentration range of 2.0 to 12.0μg/mL with correlation coefficient of 0.9934.The precision (0.4 and 0.9%RSD),accuracy (%Er=0.16),recovery (100%),limit of detection (0.29μg/mL)and limit ofquantitation(0.89μg/mL)of the method were all found to be satisfactory. No significant difference (p>0.05)was observed between the content of metronidazole assayed using the developed method and the BP method in all the samples.

Conclusion: The proposed method can be used for quantitative determination of metronidazole in pure and tablet dosage forms.