Micromeritics Flashcards
Science and technology of small particles
micromeritics
unit of measurement of micromeritics
micrometer
T/F smaller particle size –> intimate contact of drug and dissolution medium –> inc solubility and dissolution
T
Applications of micromeritics
Release and dissolution, Drug Absorption and action, Physical stability, Dose uniformity
T/F Inc solubility and dissolution decreases rate of absorption and slow onset of action
F increases and fast
T/F smaller particles increase stability
T
Methods of determining particle size
Optical microscopy, feret’s diameter, martin’s diameter, projected area diameter, sieving, sedimentation, particle volume measurement
T/F optical microscopy provides 3D images
F
particle size of optical microscopy
0.2-100 um
particle size of sieving
40-9500 um
T/F increasing mesh number decreasing particle sze
T
Apparatus used in Sedimentation
Andreasen apparatus
particle size of sedimentation
0.8-300 um
Law followed by sedimentation
stoke’s law
Terminal settling velocity of particles through a liquid medium in a gravitational centrifugal movement using Andreasen Apparatus
Sedimentation
Size of particle size measurement
0.5-300 um
Powder is suspended in an electrolyte solution and is made to flow thru a short insulated capillary section between 2 electrodes and the resistance of the system is measured
Particle size measurement
Machines in particle volume measurement
Coulter-Counter, HIAC/Royco, Gelman Counter
properties that are defined individually
Fundamental properties
properties that are dependent on the fundamental properties
derived properties
examples of derived properties
density, porosity, packing arrangement, flow properties
examples of fundamental properties
size and shape, size distribution
difference between the bullk volume and true volume
void volume
measure of the void volume in a powder material
porosity
total volume of the material
bulk volume
T/F bulk volume is measured with a beaker
F. grad cyl
equal to true volume + interparticle pores
specific granule volume (Vg)
equal to true volume + interparticle pores + spaces between pores
specific bulk volume (Vb)
excludes the volume of pores and interparticle spaces
true density or absolute density
instrument to measure true or absolute density
helium densitometer
includes the pore volume but excludes the interparticle spaces
apparent or envelope density
apparent or envelop density is based on
liquid displacement
includes both pore volume and interparticle spaces
Bulk density
describes the packing of particles or granules
Bulk density
Method I for Bulk density
Graduated cylinder
Method II for Bulk density
Volumeter
example of volumeter
scott volumeter
Method III for Bulk density
Vessel
Define bulk density:
- increase granule size
2. less spherical
- decrease
2. decrease
T/F an increase in BD will cause an increase in porosity hence increasing interparticle contact and inc cohesion
F. decrease porosity dapat
reflects maximum packing density of a powder achieved under the influence of well-defined, externally applied force
Tapped density
ease with which a powder will flow under a set of conditions
Powder flowability
T/F angle of repose is an intrinsic property
F
T/F angle of repose depends upon the method used
T
Characteristic of the internal friction or cohesion of the particles
Angle of repose
T/F if powder is very cohesive, the heap is characterized by only one angle of repose
F. >1
measures the angle of pile of material at rest and gives some recognition of a powders ability to flow
angle of repose
T/F rough and more irregular surface of particles –> lower angle of repose
F. Higher dapat
T/F compressibility index is an intrinsic property
F
measures propensity of a powder to be compressed
Compressibility facto
T/F Higher Carr’s compressibility index, more free flowing
F
T/F higher hausner ratio, less free flowing
T
more cohesive powders have hausner ratio greater than ___
1.6
T/F coarse spheres have high interparticle friction
F low
T/F free flowing powders have closer values of bulk and tapped densities
T
give 2 manufacturing problems
uneven powder flow; caking; segragation in blending; transfer of powders thru hoppers
Stages in tablet formation
Die filling, Tablet formation, Tablet rejection
Components of a tablet press
HDPCFUD
pharmaceutical process that converts a mixture of powders, which have poor cohesion, into aggregates capable of compaction
Granulation
T/F Granulation prevents seggragation
T
