Chemical and physicochemical characterization of petrolatums used in eye ointment formulations

Petrolatums from different manufacturers were characterized by viscosity measurements, oil number and ratio of low to high mol. wt components (capillary gas chromatography). Viscosity measurements and oil numbers of original materials did not correlate with the viscosity of the processed material in eye ointments. The ratio of high carbon number components to the low carbon number components was a reliable predictor for the viscosity of the formulation.