Abstract
A simple liquid chromatographic method for simultaneous quantification of diethylamine salicylate and methyl nicotinate in the presence of parabens and some drug degradation products is demonstrated. The LC-separation of the two drug substances was undertaken on a column packed with μ-Bondapack C18 using 1% aqueous acetic acid-acetonitrile (85 + 15) at a flow rate of 1.7 ml/min at ambient temperature with detection at 254 nm. Gradient mixing was adopted after 12 min to enhance the rapid elution of the component propyl paraben and other firmly adsorbed ingredients in the ointment base. Good percent assay and mean recoveries with low deviations were obtained for each added drug substance. The stability indicating characteristic of the investigated procedure shows its advantage over another HPLC-method.