Analysis of etimicin sulfate by liquid chromatography with pulsed amperometric detection

A new method for determination of etimicinʹs (ETM) purity and content is developed by liquid chromatography (LC) and pulsed amperometric detection (PAD). A reversed-phase ion-pair LC method with pulsed amperometric detection on a gold electrode after post-added NaOH is described. The mobile phase consisted of an aqueous solution containing 0.033 mol L−1 oxalic acid, 0.012 mol L−1 heptafluorobutyric acid, and 210 mL L−1 acetonitrile with pH 3.40 adjusting by dilute NaOH solution. The total analysis time was not more than 30 min. The effects of the different chromatographic parameters on the separation were also investigated. A number of commercial samples of etimicin sulfate were analyzed using this method.