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 C-18 (3.9 x 150 mm, 4 mu m) 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 mu g/ml of MB, 0.8 to 8.0 mu g/ml of MP, and 0.2 to 2.0 mu g 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.