Title: Experiment 4 (Part A)
- Sieving
Date of experiment: 24th
November 2016
Objectives
To determine the particle
size and the size distribution of lactose and microcrystalline cellulose (MCC)
by using sieve nest.
Introduction
A sieve, or sifter,
is a device for separating wanted elements from unwanted material or for
characterizing the particle size distribution of a sample. Sieving is a simple
method for separating particles of different sizes. It is a generally utilized
technique for particle size analysis and sort a large amount of particles to
various size ranges. In this practical, sieving is used to
determine the particle size and the size distribution of lactose and
microcrystalline cellulose (MCC) by using sieve nest.
Apparatus and materials
Sieve nest, spatula,
weighing boat, electronic balance, lactose and microcrystalline cellulose
(MCC).
Procedure
1.
100g
lactose is weighed.
2. The
sieve nest is prepared in descending order (largest diameter to the smallest,
from top to bottom)
3. The
powder is placed at the uppermost and the sieving process is allowed to proceed
for 10 minutes.
4. Upon
completion, the powder collected at every sieve is weighed, the particle size
distribution is plotted in the form of histogram.
5. Steps
1-4 is repeated using lactose for 20 minutes.
6. The
above process (steps 1-5) is then repeated using MCC.
RESULT
LACTOSE
SIZE OF THE SIEVE
NEST (micrometre)
|
LACTOSE
|
||||
10 MINUTES
|
20 MINUTES
|
||||
WEIGHT (g)
|
FREQUENCY (%)
|
WEIGHT (g)
|
FREQUENCY (%)
|
||
710
|
x < 710
|
16.6162
|
16.76
|
3.23
|
2.63
|
600
|
600 < x ≤ 710
|
44.2657
|
44.64
|
3.01
|
2.45
|
425
|
425 < x ≤ 600
|
0.6282
|
0.63
|
2.70
|
2.20
|
300
|
300 < x ≤ 425
|
26.4944
|
26.72
|
18.15
|
14.79
|
150
|
150 < x ≤ 300
|
0.8332
|
0.84
|
23.79
|
19.39
|
53
|
53 < x ≤ 150
|
10.0649
|
10.14
|
54.00
|
44.01
|
50
|
50 < x ≤ 53
|
0.2128
|
0.21
|
12.57
|
10.24
|
<50
|
x ≤ 50
|
0.0501
|
0.05
|
5.26
|
4.28
|
TOTAL
|
99.1655
|
100.00
|
122.71
|
100.00
|
|
LACTOSE
10 MINUTES
20 MINUTES
MICROCRYSTALLINE
CELLULOSE (MCC)
SIZE OF THE SIEVE NEST
(micrometre)
|
PARTICLE SIZE RANGE
(micrometre)
|
MICROCRYSTALLINE
CELLULOSE (MCC)
|
|||
10 MINUTES
|
20 MINUTES
|
||||
WEIGHT (g)
|
FREQUENCY (%)
|
WEIGHT (g)
|
FREQUENCY (%)
|
||
710
|
x < 710
|
0.0126
|
0.02
|
2.8085
|
2.3
|
600
|
600 < x ≤ 710
|
0.1159
|
0.12
|
2.7503
|
2.25
|
425
|
425 < x ≤ 600
|
0.1267
|
0.13
|
3.0490
|
2.49
|
300
|
300 < x ≤ 425
|
1.2817
|
1.29
|
3.9029
|
3.20
|
150
|
150 < x ≤ 300
|
0.4695
|
0.47
|
3.1775
|
2.60
|
53
|
53 < x ≤ 150
|
3.4532
|
3.48
|
5.4994
|
4.51
|
50
|
50 < x ≤ 53
|
60.1720
|
60.59
|
42.5846
|
34.90
|
<50
|
x ≤ 50
|
33.6766
|
33.91
|
58.2404
|
47.74
|
TOTAL
|
99.31
|
100.01
|
122.01
|
100.00
|
|
MICROCRYSTALLINE CELLULOSE (MCC)
10 MINUTES
20 MINUTES
DISCUSSION
In this experiment, sieving method
is used to determine the particle size distribution of lactose and
microcrystalline cellulose (MCC). For each substance, different duration of
sieving was used which were 10 minutes and 20 minutes. Sieving method or particularly
called the sieving analysis technically involved the usage of sieve nests
stacked together based on different range of diameter of the pores on the nest.
The sieve nest arrangement in this experiment is descending from the biggest
size on the top followed by the smallest sieve nest at the bottom. With the
arrangement of the sieve nest, we placed the 710 micrometre aperture sieve nest on the
topmost layer followed by the sieve nests with aperture of 600 micrometre, 425 micrometre, 300 micrometre, 150 micrometre, 53 micrometre, 50 micrometre and the sieve neat with the
aperture <50 micrometre.
Throughout
this discussion, we will compare the difference of the histogram obtained and
how does the duration of sieving can affect the histogram pattern. From the
data obtained, the weight of the lactose obtained after 10 minutes of sieving
was 99.1655g and the pattern of the histogram plotted was randomly distributed
with no significant shape which means the particles size distribution in
lactose was random. The lactose particles was recorded to be the most in the sieve
nest with 600 micrometre of diameter with a value of
44.2657g and the lowest amount was in the <50 micrometre sieve nest. To compare with the
value obtained after 20 minutes of sieving, the weight of the lactose after 20
minutes of sieving is 122.01 and the pattern of the histogram plotted was bell
shaped. The lactose particles were collected the most from the sieve nest with
the smallest aperture of 53 micrometre which allowed particle size
ranging from 53 micrometre < x ≤ 150 micrometre weighted 44.01g.
We
can say that during the 10 minutes of sieving, the force of the sieving and the
shorter period of time was not enough to disperse the particles size
accordingly and the particles could not settle down passed the aperture of the
sieve. Only after 20 minutes of sieving, did the lactose particles disperse
accordingly by the size. As for the sieving of the Microcrystalline Cellulose (MCC),
the weight obtained after 10 minutes of sieving was 99.31 and it showed a loss
in the original mass of the MCC. The weight recorded for each particle size
distribution presented no significant pattern and the histogram pattern of the
MCC particle size distribution only can be seen after 20 minutes of sieving.
The particle of the MCC after 10 minutes of sieving was collected the most in
the sieve nest of aperture: 50 micrometre with particle ranging from 50 micrometer < x ≤ 53 micrometre.
After
20 minutes of sieving, the histogram obtained was right skewed and the
particles size were collected the highest at the sieve nest with an aperture of
< 50 micrometre. From both the histogram
plotted in MCC sieving, the same explanation as in sieving of lactose, the
force of the sieving and the shorter period of time was not enough to disperse
the particles size accordingly and the particles could not settle down passed
the aperture of the sieve. To compare between the particles size distribution
of lactose and CCM, we can say that the particles of MCC is finer than the
lactose based on the histogram plotted in which particles size of lactose
particle is collected the most ranging from 53 micrometre < x ≤ 150 micrometre and the size of MCC collected
was the most ranging x ≤ 50 micrometre.
Several
errors have arisen in this experiment and caused the graphs obtained was not
obeying the theory. The major error that can affect the mass of the powder
collected is due to the unclean sieve nest. Supposedly the total weight of the
lactose to be collected was 100 g but the obtained weight was exceeding in the
20 min of sieving for both lactose and MCC, and the weight of lactose and MCC
was lesser than 100 g in the 10 minutes sieving process. Since the sieve nest
is used by the previous group, even though same type of powders is used in the
nest, there might be leftover of the powders being left behind in the sieve
nest aperture. To overcome this, the sieve nest that is used must be cleaned by
brushing the powders off the aperture before the experiment can be done.
Besides,
error could also arise from the improper handling of the powder during the
weighing process. To transfer the powder from the sieve nest could lead to loss
in small amount of the powder due and also contamination from the foreign dust
that will affect the weight of the powders. To prevent this, the sieve nests
must be stacked tightly to the machine to avoid any leakage of the powder and
also we used newspaper to collect the powders that escaped from the aperture to
minimize error. Error could also occur from the exposure of the powder to the
air since water vapour could cause the powders to aggregate and it will affect
the weight of the powder measured.
CONCLUSION
In
the experiment, the particle size and the size distribution of lactose
and microcrystalline cellulose (MCC) by using sieve nest successfully
determined.
QUESTIONS
EXPERIMENT 4 (SIEVING)
1. WHAT
ARE THE AVERAGE PARTICLE SIZE FOR BOTH LACTOSE AND MCC?
The average particle size for MCC under 20 minutes
is below 50 mic and the average particle size of MCC under 10 minutes is 50
mic. The average particle size for lactose under 20 minutes is 53 mic whereas
the average particle size for lactose under 10 minutes is 600 mic.
2. WHAT
OTHER METHODS CAN YOU USE TO DETERMINE THE SIZE OF PARTICLE?
Other methods that can be used to determine the size
of particle are air elutriation analysis, photoanalysis, optical counting
methods, electroresistance counting methods, sedimentation techniques, laser
diffraction methods, laser obscuration time, acoustic spectroscopy and air
pollution emissions measurements.
3. WHAT
ARE THE IMPORTANCE OF PARTICLE SIZE IN A PHARMACEUTICAL FORMULATION?
The particle size is important as the size,
distribution and shape of the particles can affect bulk properties, product
performance, processability, stability and appearance of the end product.
Furthermore, the link between particle size and product performance is well
documented with regards to dissolution, absorption rates and content
uniformity.
REFERENCES
:
http://www.horiba.com/scientific/products/particle-characterization/applications/pharmaceuticals/
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