Characterization of dynamically prepared phospholipid-modified reversed-phase columns

We have modified a reversed-phase (RP8) column by passing through it an aqu eous solution of phosphatidylcholine-based liposomes. The phospholipids fro m the liposomes adsorb onto the octyl chain of the stationary phase, thus a ltering the nature of the stationary phase and of the chromatographic inter actions. The properties of the phospholipid-modified column were investigat ed using solutes belonging to several chemical classes. We found that the r etention factors of negatively and positively charged solutes decreased as the amount of phospholipid in the column was increased. For the salutes stu died here the extent of the decrease was smaller for the positive solutes. With neutral solutes, the retention factors of some (benzenediols) increase d markedly while with others (ketones) the retention factors decreased. The selectivities between the various solutes on the phospholipid-modified col umn were different than on the original reversed-phase column. The retentio n behavior of the solutes can be explained in terms of (1) effective shield ing of the hydrophobic part of the stationary phase by the polar head group s of the phospholipids and (2) hydrogen bond formation between the solutes and the carbonyl oxygens as well as the non-ester phosphate oxygens in the polar head groups of the phospholipids. (C) 2001 Published by Elsevier Scie nce B.V.