TITLE:
Sieving
Sieving
OBJECTIVE:
To determine the particle size distribution of the powder material and the size of the solid particles by using sieve nest.
To determine the particle size distribution of the powder material and the size of the solid particles by using sieve nest.
DATE OF EXPERIMENT:
20th November 2014
20th November 2014
INTRODUCTION:
Sieve
analysis helps to determine the particle size distribution of the coarse and
fine aggregates. A sieve analysis can be
performed on any type of non-organic or organic granular materials including
sands, crushed rock, clays, granite, feldspars, coal, soil, a wide range of
manufactured powders, grain and seeds, down to a minimum size depending on the
exact method. A sieve test is
performed by first assembling a stack of interlocking sieves. In this stack the
sieve with the largest openings is at the top each lower sieve will have a
smaller opening than the one above it. A pre-weighed sample of the material to
be tested is placed in the top sieve. This sieve stack is the shaken until all the material
has either been retained on a sieve or passed through.
The material retained in each sieve is weighed and compared to the weight on
the other sieves. A sieve test analysis or distribution is calculated which
shows the proportion of each particle size category in the sample.
Test Sieve Machine
|
The
materials which are tested in this experiment are lactose and microcrystalline
cellulose. The lactose is first weighed and is poured into the sieve stack
before being sieved by using mechanical shaker for a fixed amount of
time. At the end of the experiment, the weight of lactose is recorded and the
experiment is repeated by using microcrystalline cellulose. The overall results
are then presented in histograms.
MATERIALS:
·
Lactose powder
·
Microcrystalline cellulose (MCC)
APPARATUS:
·
Sieve nest
·
Spatula
·
Weighing boats
·
Electronic balance
PROCEDURE:
1.
100g lactose was weighed.
2.
A 'sieve nest' was prepared in ascending order and the
given size of the sieve.
3.
The lactose powder was put into the uppermost sieve.
4.
The lactose powder was sieved for 10 minutes.
5.
The weight of lactose powder collected at every sieve
was recorded at the end of the experiment and histograms of particle size
distribution was plotted.
6.
The above process was repeated using MCC.
DISCUSSION:
From this experiment, there are two materials that have been
observed which are lactose and microcrystalline cellulose (MCC). The method
used was sieving method, where we able to determine the particle size
distribution. Sieve analysis consists of shaking the lactose and MCC sample
through a set of sieves that have progressively prepare in descending order
which is, larger diameter on the top while smaller diameter on the bottom. The
sieve that have diameter of 500 µm are on the top and followed by 425 µm,
300µm, 200 µm, 150 µm, 53 µm, <53 µm. The results of sieve analysis are
generally expressed as the frequency of total weight of lactose or MCC/
particle size distribution of the powder that
passed through different sieve.
From
this experiment it shows that most particles size of lactose are in the range
of 50 - 150µm followed by range of 0 – 50µm respectively. While as for MCC,
most particles size are in the range of 0 – 53 µm followed by a range of 53 –
150 µm.
At the end of the
experiment, lactose and MCC used were collected back and were weighed. It was
found that the total mass sample for lactose after sieving was 99.7419 g compare
to the initial mass which was 99.9779 g. The total mass change from 99.9779 g to
99.7419.
Meaning that, 0.2360 g was missing during sieving process. Meanwhile, same goes
to MCC. The results for the total mass sample for MCC after sieving is smaller
than the total mass before sieving. The initial weight for MCC was 101.0179 g while,
upon completion, the weight was 100.1651 g. This mean, 0.8528 g of MCC was
missing. This is probably because of the small particles of sample powder might
missing during the sieves are being vibrated. Besides, some particles,
especially the finer ones, might still adhesive attached to the sieve nest thus
were not weighed. From this experiment, we found that, most particles in MCC
is smaller than those of lactose.
As
the recommendation, the screen on the sieves should be clean carefully in order
to remove all the sample powders. The stack of the sieves on the sieve nest
must be locked tidily to avoid them from moving away during shaking process.
Beside, make sure that all the left over sample powders in each sieve is
transferred to the container use in weighing process for a better result.
RESULT:
Size diameter of aperture (µm)
|
Particle size range (µm)
|
Lactose
|
|
Weight (g)
|
Frequency (%)
|
||
<50
|
0<x≤50
|
4.9536
|
4.9547
|
50
|
50<x≤150
|
93.1901
|
93.2107
|
150
|
150<x≤200
|
1.2056
|
1.2057
|
200
|
200<x≤300
|
0.3625
|
0.3626
|
300
|
300<x≤425
|
0.0082
|
0.0082
|
>425
|
425<x≤500
|
0.0000
|
0.0000
|
Total weight (g)
|
99.7419
|
||
Size diameter of aperture (µm)
|
Particle size range (µm)
|
MCC
|
|
Weight (g)
|
Frequency (%)
|
||
<53
|
0<x≤53
|
60.0473
|
59.9484
|
53
|
53<x≤150
|
34.1569
|
34.1106
|
150
|
150<x≤200
|
3.2373
|
3.2320
|
200
|
200<x≤300
|
1.7847
|
1.7818
|
300
|
300<x≤425
|
0.9293
|
0.9278
|
>425
|
425<x≤500
|
0.0096
|
0.0096
|
Total weight (g)
|
100.1651
|
||
QUESTION:
1.
What
are the average particles size of lactose and MCC?
The average particles size of lactose is 50<x≤150 µm while for MCC is
0<x≤53 µm
2.
Are there any other methods that can
be used to determine certain particle size?
Yes. The methods that can be used to determine certain particle size are microscope
methods, coulter
counter, laser light scattering method, dynamic
light scattering method, sedimentation method, air
elutriation, photo analysis and optical counting methods.
3.
What is the importance
of particle size in a formulation?
Particle size in a certain
formulation is important in achieving optimum production of efficacious
medicines especially in pharmaceutical phase. It can influence the
bioavailability and activity of drug. For example, it can influence segregation
behaviour, the ease with which powder flows through the press and the
compressibility of a formulation. This factor of formulation also can influence
the disintegration and dissolution rate in the body cavity.
CONCLUSION:
The objective to determine the size distribution of the sample of
powders by sieve analysis is achieved. Most particles size of lactose are in
the range of 50 - 150µm followed by range of 0 - 50µm respectively. While as
for MCC, most particles size are in the range of 0 - 53µm followed by a range
of 53 – 150µm. This shows that most particles in MCC is smaller than those of
lactose.
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