Liquid chromatography of gramicidin

A simple, selective method is described for separation of more than 10 gram icidin components on Spherisorb ODS B, 5 mum, 250 x 4.6 mm I. D. column, ma intained at 50 degreesC. The mobile phase comprised methanol-water (71:29) at a flow rate of 1.0 mL min(-1). Detection was by UV at 282 nm. Valine gra micidins A, B and C were very well separated from the isoleucine gramicidin s A, B and C. Four new gramicidin components were also resolved and their s tructures determined by liquid chromatography/mass spectrometry. The names 10-methionine valine gramicidin C, 4-methionine valine gramicidin A, valine gramicidin A hydroxypropyl and isoleucine gramicidin A hydroxypropyl were proposed. Robustness of the liquid chromatography method was evaluated by p erforming a full factorial design experiment. The method also showed good r epeatability, linearity and sensitivity.