Title
Sieving
Objective
To determine the presence of agglomerate,
particle size distribution and average size of particles
Date of Experiment
30th September 2014
Introduction
Sieving is used to separate and break up clumps in dry powders by using sieve. Sieve is a device with meshes or perforations through which finer particles of a mixture (as of ashes, flour, or sand) of various sizes may be passed to separate them from coarser ones. Each lower sieve in the column has smaller openings than the one above. At the base is a round pan, called the receiver. The column is typically placed in a mechanical shaker. The shaker shakes the column, usually for some fixed amount of time.
A suitable sieve size for the aggregate should be selected and placed in order of decreasing size, from top to bottom, in a mechanical sieve shaker. A pan should be placed underneath the nest of sieves to collect the aggregate that passes through the smallest. The entire nest is then agitated, and the material whose diameter is smaller than the mesh opening pass through the sieves.
Sieving is used to separate and break up clumps in dry powders by using sieve. Sieve is a device with meshes or perforations through which finer particles of a mixture (as of ashes, flour, or sand) of various sizes may be passed to separate them from coarser ones. Each lower sieve in the column has smaller openings than the one above. At the base is a round pan, called the receiver. The column is typically placed in a mechanical shaker. The shaker shakes the column, usually for some fixed amount of time.
A suitable sieve size for the aggregate should be selected and placed in order of decreasing size, from top to bottom, in a mechanical sieve shaker. A pan should be placed underneath the nest of sieves to collect the aggregate that passes through the smallest. The entire nest is then agitated, and the material whose diameter is smaller than the mesh opening pass through the sieves.
Apparatus
Weighing machine,
sieve nest, weighing boat
Material
Lactose,
microcrystalline cellulose (MCC)
Procedure
1. 100g of lactose is weighed by using weighing machine.
1. 100g of lactose is weighed by using weighing machine.
3.The lactose is put into the
sieve.
4.Sieving process is started
with appropriate speed for 20 minutes.
5.The product inside each sieve
nest is weighed after the sieving process.
6.The particle size
distribution graph is plotted with the method used.
7.The process is repeated by
using MCC.
Particle Size Distribution Graph
1. What are the average
particle size for both lactose and MCC?
Result
Bil
|
Size
of sieve nests
(micrometer)
|
Weight
of small weighing boat (g)
|
Weight
of small weighing boat and lactose (g)
|
Weight of lactose
obtained (g)
|
1
|
425
|
2.0941
|
20.6506
|
20.6506
- 2.0941 = 18.5565
|
2
|
300
|
2.1725
|
44.9483
|
44.9483
- 2.1725 = 42.7758
|
3
|
200
|
2.1946
|
17.4742
|
17.4742
- 2.1946 = 15.2796
|
4
|
50
|
3.1789
|
25.7004
|
25.7004
- 3.1789 = 22.5215
|
5
|
Base
|
3.2454
|
3.8539
|
3.8539
- 3.2454 = 0.6085
|
Bil
|
Size
of sieve nests
(micrometer)
|
Weight
of small weighing boat (g)
|
Weight
of small weighing boat and MCC (g)
|
Weight of MCC
obtained (g)
|
1
|
425
|
2.0370
|
2.1420
|
2.1420
– 2.0370 = 0.1050
|
2
|
300
|
3.1788
|
5.1400
|
5.1400
– 3.1788 = 1.9612
|
3
|
200
|
3.2500
|
34.2381
|
34.2381
– 3.2500 = 30.9881
|
4
|
50
|
5.6449
|
69.8374
|
69.8374
– 5.6449 = 64.1925
|
5
|
Base
|
2.7726
|
5.5256
|
5.5256
– 2.7726 = 2.7530
|
Particle Size Distribution Graph
Discussion
Sieving is an efficient tool for
separating particle according to size of particles. It is used to classify and
determine the properties of certain sample which have larger overall particle
size, typically using a woven screen such as a mesh or net.
There are some errors occurred in
this experiment. The samples are exposed to air and may absorb moisture which
can affect the particle size distribution. Particle may clump together after
absorbing the moisture. Some of the fine particles may form dust and lost which
can affect the weight of sample at each sieve nest after sieving.
Precautions should be taken to
reduce the errors occurred. The sample should be weighted and poured into the
sieving machine immediately to minimize the exposure to air. Besides the sieve
nests should be left alone for few minutes after vigorous shaking completed to
reduce the fine particles come up and diffuse in the air. The fine particles
should be settled down first before open up the sieve nest for weighing
purpose.
Questions
Lactose
has average particle size of 300µg while average particle size for MCC is 50µg.
2. What other methods can you use to
determine the size of particle?
The
other methods to determine particle size are microscopy, sedimentation
techniques, optical and electrical sensing zone method, laser light scattering
techniques and surface area measurement techniques.
3. 3. What are the importance of
particle size in a pharmaceutical formulation?
The size, distribution and shape
of the particles can affect bulk properties, product performance, flowability, stability, disintegration and
dissolution and appearance of the end product.
Conclusion
From
this practical, we can know that there are no agglomerates present in the
sample, particle size distribution and particle size can be determined by using
sieving method.
Reference
1. http://en.m.wikipedia.org/wiki/Sieve
2. Aulton. M.E. 2002. Pharmaceutics: The
Science of Dosage Form Design, 2nd Edition. Churchill Livingstone.
3. http://www.cscscientific.com/particle-size/sieves
No comments:
Post a Comment