Narrow-bore reversed-phase liquid chromatography of metronidazole benzoate and its hydrolysis products

A stability-indicating HPLC assay for metronidazole benzoate

“…The LOQ values reported previously for the HPLC assay procedures for metronidazole benzoate are 20 g ml −1 or higher [4,[7][8][9]. Our preliminary results suggest that these values are too high to obtain a reliable dissolution profile of the ester in water due to the poor aqueous solubility of the drug (see later).…”

“…Metronidazole (free base) is eluted either with or very close to the solvent front in all the cases when we used previously reported stability-indicating HPLC assay procedures [4,7,8]. This makes detection of metronidazole, one of the degradation products, ambiguous and its accurate quantitation difficult.…”

“…The previous procedures used C18 columns [4,7,8]. When we changed to a C8 column to reduce hydrophobicity of the column to increase retention of protonated metronidazole (under the elution condition), it eluted after the solvent, permitting us to quantitate metronidazole benzoate, metronidazole and benzoic acid in the same run with an overall analysis time of about 6 min ( Fig.…”

“…In a stability study of metronidazole benzoate, Matthew et al [4] used two different HPLC procedures, one for metronidazole benzoate and the other for its degradation products. In addition, the limit of quantitation (LOQ) of metronidazole benzoate in the previous reports [4,[7][8][9] are too high (20 g ml −1 or higher) for many analytical applications due to its poor aqueous solubility.…”

“…Stability-indicating HPLC assay procedures for metronidazole benzoate have been reported [4,7,8]. However, in all the cases, metronidazole (free base), one of the degradation products of metronidazole benzoate, is eluted very early, either with or very close to the solvent front.…”