Hydrophilic–Lipophilic Balance Concept: The HLB concept was introduced by Griffin in 1947 to classify nonionic surfactants but has since been applied to ionic surfactants as well. In this system, each surfactant is assigned a number between 1 and 20, representing […]
Ring Detachment Method (du Nouy tensiometer): The du Nouy’s ring method is similar to the Wilhelmy plate method, but it uses a ring or loop of wire. A platinum or Iridium wire of ~4 cm in circumference is suspended from […]
Sedimentation Technique: Equivalent diameter: Stokes’ diameter; frictional drag diameter—a sphere having an equivalent drag force to a particle of the same diameter in the same fluid at the same velocity. Range of analysis: 1 μm to about 200 μm. It […]
Matter: The definition of Matter is anything that has mass and volume (takes up space). States of matter: Matter exists in one of the three states-solid liquid or gas. Two factors usually determined the state in which matter exist. One is the intensity of […]
Average particle size: Suppose that the particle size of a powder is analysed and the number of particles in each size range is determined, from the data, the average particle size of the powder may be calculated as Davg = […]
Specific surface: The specific surface of a powder is defined as the surface area per unit volume (Sv) or per unit weight (Sw). SURFACE AREA DETERMINATION METHODS: The surface area can be determined directly by one of the following two […]
Density (Ƿ): Density is defined as weight per unit volume. Based on the types of volume defined, the corresponding ‘density’ may be proposed. Table 1 – Types of densities Density Dełnition Formula Determination Comment Bulk(Ƿb) Mass divided by bulk volume […]
A Pharmaceutical suspension is a coarse dispersion in which internal phase (therapeutically active ingredient)is dispersed uniformly throughout the external phase. The internal phase consisting of insoluble solid particles having a range of size(0.5 to 5 microns) which is maintained uniformly […]
SEDIMENTATION OF FLOCCULATED PARTICLES: When sedimentation is studied in flocculated systems, it is observed that the flocs tend to fall together, producing a distinct boundary between the sediment and the supernatant liquid. The liquid above the sediment is clear because even […]
WETTING OF PARTICLES: The initial dispersion of an insoluble powder in a vehicle is an important step in the manufacturing process and requires further consideration. owders sometimes are added to the vehicle, particularly in large-scale operations, by dusting on the […]