Surface pressure and surface potential study of a synthetic phospholipid at the air/water interface

Surface pressure and surface potential measurements on monolayers of synthetic 1,2-dipalmitoyl-DL-phosphatidylethanolamine at the air/water interface indicate that the axis of the zwitterion is parallel to the surface. Many two-dimensional arrangements in this plane are energetically possible. Surface phase dissociation constants of the zwitterion functional groups are calculated from surface potential data, and the effect on the monolayer of differing cations in the subphase is described.