SPINNING BUBBLE TENSIOMETRY OF AQUEOUS DIPALMITOYLPHOSPHATIDYLCHOLINE AND LUNG SURFACTANT DISPERSIONS

A new method for measuring surface tensions of aqueous surfactants under surface compression is used. The method, spinning bubble tensiometry (SBT), is accurate, free from end effects, and precise for tensions as low as 10-4 dyn cm-1. Surface tensions of dispersions of pure synthetic L-α-dipalmitoylphosphatidylcholine (DPPC) and sheep lung surfactant extract have been studied for concentrations from 5 to 2000 ppm and temperatures from 25 to 45°C. Values of superlow surface tensions (less than 10 dyn cm-1) which were reported in the literature for compressed surfaces of DPPC and lung surfactants were accurately determined and found valid with this method. There was no correlation between the surfactant dispersion microstructure and the ability to achieve superlow tensions. However, a minimum particle concentration of the surfactant ( ∼ 0.1 wt%) was required for reproducibly observing superlow tensions. © 1990.