Im quite skeptical about this method of doing liposomes. As a lipid biophysicist I would suggest you to do the following: Dissolve your lipids in Chloroform:Methanol 9:1 volume ratio (when using short PE lipids you may require higher ratio of Methanol, e.g 1: 1). The concentration of these stock solutions are based on weight but can later be contrasted using a Phosphate determination assay (Rouser et al.) in the case of phospholipids. Later, aliquots are taken and the organic solvent is removed under N2 to prevent the oxidation of unsaturations in the acyl chains. Once dried, you add buffer and incubate the dispersion for 15 min at T>Tm . Later you do the freeze-thaw cycles, to obtain your MLVs and to stabilize the salt concentration among the different layers of your MLV. Remember that thawing must be conducted at T>Tm to ensure the permeability of the membrane. To conclude, you extrude your MLVs at T>Tm to obtain liposomes. This is the only reliable method to produce liposomes under my experience.