Simultaneous high-performance liquid chromatographic stability-indicating analysis of acetaminophen, codeine phosphate, and sodium benzoate in elixirs.

A stability-indicating high-performance liquid chromatographic method has been developed for the simultaneous determination of acetaminophen, codeine phosphate and sodium benzoate in an elixir formulation. The reversed-phase paired-ion method utilizes UV detection at 214 nm, a C18 column at 50 degrees C and requires ca. 10 min per analysis. The method has been validated for use with elixirs containing 120 mg of acetaminophen, 12 mg of codeine phosphate and 7.5 mg sodium benzoate preservative per 5 ml. The known potential degradation products p-aminophenol, codeine N-oxide and codeinone are separated for quantitation simultaneous with the parent compounds. The method has been shown to be linear, reproducible, specific, sensitive and rugged.