Liquid chromatographic determination of pentaerythritol tetranitrate in pharmaceuticals: collaborative study

A liquid chromatographic (LC) method for the determination of pentaerythritol tetranitrate (PETN) in pharmaceutical formulations and the bulk drug triturate was evaluated in an interlaboratory study that included 12 participating laboratories. The procedure involves extraction of the active ingredient with mobile phase, followed by filtration of the extract and reverse-phase liquid chromatography using an octadecylsiliane bonded phase column and UV detection at 230 nm. The mobile phase composition is 35% water in acetonitrile (v/v). Three bulk drug samples (20, 20, and 35% PETN), 2 commercial tablet formulations (20 and 80 mg PETN/tablet), and 1 commercial capsule formulation (45 mg PETN/capsule) were analyzed in duplicate by the proposed method. Repeatability (sr, RSDr) and reproducibility (SR, RSDR) based on peak height measurement for these samples ranged from 0.0066 to 0.1806 (0.53-3.36%) and 0.0165 to 0.2075 (0.76-3.86%), respectively. Results for peak area measurements ranged from 0.0145 to 0.2011 (0.93-3.74%) and 0.0231 to 0.2091 (1.28-3.89%), respectively. The method has been approved interim official first action by AOAC.