Liquid chromatography determination of liposome components using a light-scattering evaporative detector

Analysis of liposomal components is important in stability testing of formulations. An LC method for the analysis of liposomal components cholesterol, phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine and their lyso-forms was developed. The method uses a light-scattering evaporative detector and isocratic mobile phase. In addition, components of pH-sensitive liposomes, cholesterylhemisuccinate and cationic lipid dimethyldioctadecylammonium bromide used in transfections were determined by the method. The separations were carried out on a Spherisorb S5 NH2 cartridge column or Zorbax NH2 column (25 cm x 4.6 mm, 5 microns particle size). The mobile phase consisted of acetonitrile-methanol-ammonium acetate solution (pH 4.8, 0.1 M) (52:32:16, v/v/v) at a flow rate of 2 ml min-1. Detection limits were 1.3-8.0 micrograms ml-1 depending on the lipid. The precision (RSD) of the method was 1.5-3.3% for lipid standard solutions at 50 micrograms ml-1 concentration and 2.0-11.8% for lipids analyzed from liposome suspensions.