Spectrophotometric Determination of Metronidazole via Diazotization Reaction with p-Hydroxy Benzaldehyde as a Coupling Reagent

A new, simple and sensitive spectrophotometric method for the determination of Metronidazole (MN) has been developed. The method is based on reduction of nitro group of MN to amine group by Zn dust and concentrated hydrochloric acid in hot ethanol under stirring then the diazonium ion was prepared and coupled with para-Hydroxyl Benzaldehyde (p-HB) to yield, insoluble water yellow dye indicated at 410 nm. The linearity of the method was between 5.8x10–5-52.2x10–5 M, the molar absorptivity was 7131.121 L/mol/cm and Sandell index was 0.0240 μg cm–2. The method has been successfully applied to the assay of MN in pure and pharmaceutical forms.