Mixing may be defined as a unit operation that aims to treat two or more components, initially in an unmixed or partially mixed state, so that each unit (particle, molecule, etc.) of the components lies as nearly as possible in contact with a unit of each of the other components. If this is achieved, it […]
Size separation, also known as particle size classification, is a fundamental process in pharmaceutical, chemical, and material sciences used to separate particles based on their size. It ensures uniformity, quality, and performance of products by dividing a mixture of particles into fractions of similar dimensions. Size Separation Efficiency The efficiency with which a powder can […]
Dynamic light scattering (DLS) techniques have been the mainstay for the determination of particle size and particle size distributions. When light is directed at a particle, it can either be deflected or absorbed by the particle, which is dependent on the size of the particle relative to the wavelength of the light. Sample Preparation for […]
Laser diffraction (low-angle laser light scattering) is one of the most widely used techniques for particle size analysis in the pharmaceutical industry. It determines the particle size distribution of a sample by measuring the angular variation in the intensity of light scattered as a laser beam passes through a dispersed particulate sample—either in liquid suspension […]
Counter Coulter (electrical sensing zone ), which is recently developed method for the determination of particle size, is based on conductivity measurement. Sample Preparation for Coulter Counter Powder samples are dispersed in an electrolyte to form a very dilute suspension, which is usually subjected to ultrasonic agitation, for a period, to break up any particle […]
Sedimentation analysis may be used over a size range of 1 to 200 μm to obtain a size-weight distribution curve and to permit the calculation of particle size. The sedimentation analysis is based on the dependence of the rate of sedimentation of the particles on their size as expressed by Stokes’s equation. Stokes’s law is […]
Microscopic analysis is one of the most precise particle size determination methods, since individual particles are measured by direct viewing of the particles, instead of statistically averaging the diameter of a group of particles. Microscopy is often used to verify another particle sizing method, during development and validation of a particle sizing method. Microscopy measures […]
Sieve analysis uses a woven, punched or electroformed mesh, often made from stainless steel or brass, with known aperture dimensions which forms a physical barrier to the particles. Range of Particle Sizes Measured by Sieve Analysis The International Organization for Standardization sets a lowest sieve diameter of 45 µm and, as powders are usually defined […]
To obtain equivalent sphere diameters with which to characterize the particle size of a powder, it is necessary to perform a size analysis with use of one or more different methods. Particle size analysis methods can be divided into different categories based on several different criteria: size range of analysis; wet or dry methods; manual […]
A particle population which consists of spheres or equivalent spheres of the same diameter is said to be monodisperse or monosized, and its characteristics can be described by a single diameter or equivalent sphere diameter. However, it is unusual for particles to be completely monodisperse, and such a sample will rarely, if ever, be encountered […]