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Title: Micrometrics
Description: they are included in physical pharmacy and are also used in many other fields
Description: they are included in physical pharmacy and are also used in many other fields
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Micromeritics
Micromeritics refers to the science and technology of studying small particles, typically in the
size range of 0
...
This field involves the measurement and
analysis of various properties of particles, such as their size distribution, surface area, porosity,
and shape
Key concepts within micromeritics include:
1
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2
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3
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4
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Thus compound dissolves in a shorter time
...
•
Dissolution: the time required for dissolution of solid chemicals is shortened by the use
of smaller particles
•
Drying: the drying of wet mass may be facilitated by milling, which increase the S
...
and reduces the distance the moisture must travel with in the particle to reach the outer
surface
...
•
Lubrication: lubricant used in compressed tablets and capsules function by virtue of
their ability to coat the surface of granulation or powder
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Bulkiness increase with a decrease in particle size
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Factors that affect the Flow
properties are particle size, shape, surface texture, porosity and density
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φ = tan-1 (h/r) Here: h = height r = radius
•
Compression: The strength of compressed tablet depends on number of factor, most
important are which are particle size and compression
...
Methods for determining particle size
1- Optical microscopy (range: 0
...
2
2- Sieving (range: 40 – 9500μm)
Standard sized sieves are available to cover a wide range of sizes
...
•
The result achieved will depend on the duration of the agitation and the manner of the
agitation
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•
The stack of sieves is mechanically shaken to promote the passage of the solids
...
It is widely used as a method for the
particle size analysis
...
Most sieve analyses utilize a series, stack (Load /Mountain or nest (layer) of sieves which
have the smallest mesh above a collector tray followed by meshes which get
progressively coarser towards the top of the series
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A sieving time of 20 minutes is arbitrary and BS 1796 recommends sieving to be
continued until less than 0
...
Sedimentation (range: 08 –300μm)
By measuring the terminal settling velocity of particles through a liquid medium in a
gravitational centrifugal environment using Andreasen apparatus
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Particle volume measurement (range: 5 - 300 um)
•
In this type of machine the powder is suspended in an electrolyte solution
...
•
When a particle passes through the capillary there is a momentary peak in the resistance,
the amplitude of the peak is proportional to the particle size
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Higher surface area
brings about intimate contact of the drug with the dissolution fluids in vivo & increases the drug
solubility & dissolution
...
Higher the dissolution, faster the absorption & hence quicker
& greater the drug action
...
e the particle size in a formulation
influence the physical stability of the suspensions & emulsions
Title: Micrometrics
Description: they are included in physical pharmacy and are also used in many other fields
Description: they are included in physical pharmacy and are also used in many other fields