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 ch olesterol, phosphatidylcholine, phosphatidylglycerol, phosphatidyletha nolamine and their lyse-forms was developed. The method uses a light-s cattering evaporative detector and isocratic mobile phase. In addition , components of pH-sensitive liposomes, cholesterylhemisuccinate and c ationic lipid dimethyldioctadecyl-ammonium bromide used in transfectio ns 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 mu m 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-l. Detection limits were 1.3-8.0 mu g ml(-1 ) depending on the lipid. The precision (RSD) of the method was 1.5-3. 3% for lipid standard solutions at 50 mu g ml(-1) concentration and 2. 0-11.8% for lipids analysed from liposome suspensions.