Micromeritics is the science and technology of small particles and includes the study of the fundamental and derived properties of individual as well as a collection of particles. The micromeritic properties of a drug can be related in a significant […]
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 = […]
Optical Microscopy: Equivalent diameter: It is used to determine projected area diameter, Feret’s diameter and Martin’s diameter. Range of analysis: 1 μm to about 100 μm. Methodology: Firstly, the powdered substance is placed over the stage and obseved through the […]
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 […]
DERIVED PROPERTIES OF POWDERS: There are numerous derived properties that are based on fundamental properties. Those with particular relevance to pharmacy are discussed here. Packing geometry Porosity Density Bulkiness Flow property Packing Geometry: A set of particles can be filled […]
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 […]
Electric double layer: Particles dispersed in a liquid medium may become charged in one of two main ways. Ionic species present in a solution may be adsorbed at the surface or, alternatively, charges on the surface may arise due to […]