Adsorption Kinetics of Phospholipids at the Chloroform/Water Interface Studied by Drop Volume and Pendant Drop Techniques

The adsorption kinetics of the phospholipids l -α-dipalmitoylphosphatidylcholine (DPPC) and l -α-dimyristoylphosphatidylethanolamine (DMPE) has been investigated at the chloroform/water interface by using a steady drop (pendant drop method) and a growing drop (drop volume method) technique. Both experiments provide diffusion-controlled adsorption kinetics of the phospholipids at a liquid/liquid interface. The theoretical analysis of the adsorption kinetics has been performed on the basis of the Ward and Tordai equation. At extremely low phospholipid concentrations for both techniques a possible loss in bulk concentration is considered due to the adsorption at the drop surface. For the drop volume experiments a radial liquid flow inside the growing drop and the growing drop area are taken into account as well. Good agreement between the two experiments and with the existing theory is obtained.