Simultaneous determination of metronidazole benzoate, methylparaben, and propylparaben by high-performance liquid chromatography.

The simultaneous determination of metronidazole benzoate (MB), methylparaben (MP), and propylparaben (PP) in an oral suspension formulation was developed using high-performance liquid chromatography (HPLC). The method was developed using a Novapak C18 (3.9 x 150 mm, 4 microns) column, methanol-water (50:50, v/v) as the mobile phase and an ultraviolet (UV) detector at 254 nm. The peak area response versus concentration was linear in a concentration range from 40 to 400 micrograms/ml of MB, 0.8 to 8.0 micrograms/ml of MP, and 0.2 to 2.0 micrograms of PP. The correlation coefficients were 0.9997 for MB, 0.9987 for MP, and 0.9983 for PP, with relative standard errors of 1.12%, 1.28%, and 1.67%, respectively.