Quantification of pegylated phospholipids decorating polymeric microcapsules of perfluorooctyl bromide by reverse phase HPLC with a charged aerosol detector

Abstract

Polyethylene glycol (PEG) chains covalently linked to phospholipids are often used in the preparation of lipid or even polymer colloidal particles to avoid recognition and clearance by the reticuloendothelial system and to increase their plasmatic half-life. To the best of our knowledge, no direct method allows yet to quantify these pegylated phospholipids. The aim of this work was to develop a method for the quantification of a typical pegylated phospholipid, 1,2-distearoyl- sn-glycero-3-phosphoethanolamine- N-[methoxy(polyethylene glycol)-2000], DSPE-PEG2000, associated to polymeric microcapsules of perfluorooctyl bromide (PFOB). Reverse phase high-performance liquid chromatography (HPLC) was used, coupled with a corona charged aerosol detection (HPLC–CAD). Calibrations standards consisted of plain microcapsules and pegylated phospholipids (DSPE-PEG2000) in the concentration range of 2.23–21.36 μg/mL (0.22–2.14 μg injected). Calibration curve was evaluated with two different model, linear and power model. The power model describes experimental values better than the linear model, for pegylated phospholipids with the CAD detector. The correlation coefficient for the power model was 0.996, and limits of detection and quantification obtained were 33 and 100 ng, respectively. This method proved to be selective and sensitive; the accuracy of the method ranged from 90 to 115% and the relative standard deviation was ≤5.3%. Pegylated phospholipids associated to microcapsules, as well as the phospholipids and total phospholipids in the suspensions were successfully quantified in three different preparations of microcapsules.