how does small particle size effect absorption
faster absorption
what does particle size effect
drug bioavailability, settling rate of suspensions, obtaining and maintaining homogenous mixtures, flowability, tolerability of dosage forms
granulation effect on particle size
increases
milling effect on particle size
reduces
how does a cutter mill work
multiple blades to cut up material
how does compression (roller mills/mortar and pestle) work
pressure applies to reduce size
how does a impact methods( hammer mill) work
particles are hit by a moving surface/ moving particles hit off a surface
how does a attrition methods (different type of roller mill/mortar and pestle) work
apply pressure and friction
how does combined impact and attrition (ball mill/ fluid energy mill) work
mill rotates and balls inside hit. off the particles
coarser particles are thrown outwards and fine farticles removed
which particles are good for cutter mills
elastic, fibrous materials
which particles are good for attrition methods
ointments, solid in suspensions and pastes
which materials are best used for impact methods
brittle materials
what is project area diameter
based on a circle of equivalent area to that of the particle image
projected perimeter diameter
based on having a circle with a perimeter that fits the particle
ferets diameter
mean distance between the 2 parallel tangents ( widest way)
martin mean chord length
narrow section diameter
methods to analyse particle size
serving, microscopy (direct) , sedimentation rate and permeability (indirect )
light microscopy
1-1000nanometer, 2d image
electron microscopy
size range as low as 0.001 nanometers, 3d, these require a high level of operator expertise and are very expensive
what happens if theres too many particles
the can clump together and you only see big particles
what is the stokes equation
the rate at which particles drop to the bottom due to differemces in size and density.
how is tmax effected as particle asize increases
it increases
laser light scattering methods
laser light interacts with particles - He and Ne are the most widely used laser - light is diffracted by particles by an angle which is inversely proportional to the volume of particles.
size seperation methods
via seiving/ sedimentation - cyclone or elutriation
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