(452c) Measuring Blend Hydrophobicity By Single Droplet Penetration Technique

Hydrophobicity is recognized as a critical property for pharmaceutical intermediate blends. For lubricated blends, the hydrophobicity is especially important as it affects the drug release in later in vitro dissolution tests. Hydrophobicity also affects the characteristic wetting time during wet granulation processes. In this work, a method was developed to monitor the penetration process of a droplet on powder surface. Using a high-speed camera and video processing technique, the droplet penetration profile was obtained. As a case study, blends with varying hydrophobicity were prepared using a modified Couette shear cell. Comparison of droplet penetration profiles showed that blends with higher hydrophobicity had longer penetration time. Interestingly, a “waiting phase” was observed before the droplet initiates the penetration for less hydrophobic blends. A non-wetting liquid was used in addition to DI water. The penetration model was used to describe the droplet penetration process with the assumption of constant drawing area. The method to compare blend hydrophobicity using penetration profiles from two liquids was demonstrated. This study presented a potential technique to measure blend hydrophobicity to indicated process changes.