Liquid chromatography of polymyxin B sulphate

A reversed-phase liquid chromatography method for analysis of polymyxin B sulphate is described. The method uses a YMC-Pack Pro, C-18, 5 mu m, 250x4.6 mm I.D. column maintained at 30 degrees C. The mobile phase comprises acetonitrile-sodium sulphate (0.7%, m/v)-phosphoric acid (6.8%, v/v dilution of 85%, m/m phosphoric acid)-water (22.25:50:5:22.75) at a flow-rate of 1.0 ml/min. Detection was by UV at 215 nm. The method is able to resolve polymyxin B-1, the major component, from more than thirty other components present in the complex. Robustness was evaluated by performing a full-factorial design experiment. The method showed good selectivity, repeatability, linearity and sensitivity. (C) 2000 Elsevier Science B.V. All rights reserved.