Title : Particle Size Analysis Using
Sieving Method
Aim : To determine the particle size and size distribution of lactose powder and microcrystalline cellulose
( MCC)
Date : 19.11.2015
Introduction :
A
particle is a small object of any size range from microscopic scale to atomic
scale . It is important to determine the size of the particle for a substance
in order to obtain maximum efficacy of drug .
There are many methods that can be used for particle size analysis ,
including sieve method , microscope method , coulter counter and laser light
diffraction method . The method chose for particle size analysis is based on
criteria such as size range of analysis, wet or dry method , manual or
automatic method and the speed of analysis .
In this
experiment , sieve method are used to determine particle size and the
distributions . Sieving is an old method commonly used to break down
agglomerates , it is cheap , easy to perform and readily usable for large particle
. It is usually use on dry samples only . It is not possible to perform on
sprays and emulsions because it have very poor reproducibility for wet sieving
.
In the
sieving method , a sieve stack comprised on normally 6 to 8 sieves , with
decreasing diameter is arranged from top to the bottom . Samples are loaded to
the top sieve , that is the coarsest sieve and it is subjected to mechanical
vibration for a fixed period of time . After that , the weight of sendiment
collected at each stack is recorded and particle size analysis can be performed
.
Apparatus : Sieve nest , spatula , weighing boat ,
electronic balance .
Material : Lactose powder , microcrystalline
cellulose ( MCC ).
Procedure :
·
100g of lactose is weigh in a weighing boat using electronic balance .
·
Sieve nest is prepared in descending order from the largest diameter to the
smallest diameter from top to bottom .
·
The powder is placed at the uppermost sieve and the sieving process is
allow to proceed for 10 minutes .
·
Upon completion , the powder collected at every sieve is weighed .
·
The particle size distribution is plotted in the form of histogram .
·
The above process is repeated using MCC.
Result :
Particle size (
µm)
|
Mass of Lactose
retained in the sieve (g)
|
% retained = (w
sieve/w total )
x 100%
|
Cumulative
percentage retained
|
% passing = 100%
- cumulative percentage retained
|
>500
|
0.0392
|
0.0395
|
0.0395
|
99.9605
|
425-500
|
0.0046
|
0.0046
|
0.0441
|
99.9559
|
355-425
|
4.5063
|
4.5437
|
4.5878
|
95.4122
|
150-355
|
26.5859
|
26.8064
|
31.3942
|
68.6058
|
45-150
|
67.7878
|
68.3500
|
99.7442
|
0.2558
|
<45
|
0.2537
|
0.2558
|
100.00
|
0
|
Table 1
Figure 1
Particle size (
µm)
|
Mass of MCC
retained in the sieve (g)
|
% retained = (w
sieve/w total )
x 100%
|
Cumulative
percentage retained
|
% passing = 100%
- cumulative percentage retained
|
>500
|
0.0050
|
0.0051
|
0.0051
|
99.9949
|
425-500
|
0.0070
|
0.0071
|
0.0122
|
99.9878
|
355-425
|
0.1452
|
0.1473
|
0.1595
|
99.8405
|
150-355
|
6.5924
|
6.6879
|
6.8474
|
93.1526
|
45-150
|
88.9019
|
90.1897
|
97.0371
|
2.9629
|
<45
|
2.9206
|
2.9629
|
100.00
|
0
|
Table 2
Figure 2
Figure 3
Question :
·
What are the average particle size for both lactose and MCC ?
The average particle size for lactose and MCC
fall between range 45-150µm.
·
What other methods can you use to determine the size of particle ?
Other method to determine size of particle is
microscopy . It can be done through light microscope , transmission electron
microscope and scanning electron microscope. It is operated by directly looking
at the particles , thus determining not only the particle size but their shape
and structure as well . The next method is coulter counter method , where
powder samples must be first dispersed in an electrolyte to form very dilute
suspension , it is then place in the coulter counter , the particle size is determine
by the height of amplitude which correspond to the volume of particle displaced
through the aperture into the aperture tube . Another method is laser light
diffraction , where the detectors measure the particle size through the
interaction between the particle and the laser beam .
·
What are the importance of particle size in a pharmaceutical formulation ?
Particle size is important in the production of medicine as solid
suspended in the liquid must be uniform so that there is no agglomerates and
the content of the medicine is uniform . Particle size is important in
pharmaceutical formulation as it affect drug release and drug dissolution . The
smaller the size of the drug particle , the higher the surface of area in
contact with the medium , thus it is easier to dissolve and easier to be
absorbed by the body . Particle size also important in the case of administration
of medicine , this is to make sure that drug injected into the body will not
obstruct the blood vessels .
Discussion :
Size reduction process is also termed as communition
or pulverization. The importance of particle size reduction is to aid efficient
processing of solid particles by facilitating powder mixing or the production
of suspensions, exposing cells prior to extraction and reducing the bulk volume
of a material to improve transportation efficiency. Sieves is used to determine
the particle size and the size distribution of both powders (MCC and Lactose).
The method used of sieves is by putting MCC and Lactose powder in the most
upper sieve. Then switch the plug and it will vibrate the sieve stack for 10 minutes.
Each sieve can filter the powder to a smaller diameter. The highest diameter
for the sieve is >500 µm followed by 425-500 µm, 355-425 µm, 150-355 µm, 45-150 µm and the lowest sieve
diameter is <45 µm. After the sieving is finished. The result is obtained and recorded. The
mass of powder for each sieve is measure by analytical balance. The mass
obtained in different sieve indicates different size analysis of Lactose and
MCC. The distribution of particle size of MCC and lactose is demonstrated experimentally
in Figure 1, Figure 2, Figure 3.
Lactose and MCC have
different material properties. This differences contribute to different on size
distribution as shown in Figure 3. For Y axis for the graph is percentage of mass powder (MCC or Lactose) retained in the
sieve (g) per total mass of powder inserted times 100. (% retained = (w sieve/w
total) x 100%). For X axis is Particle size (µm). Based on data collected in
the experiment particle size (µm) for MCC is >500 and the percentage
retained is 0.0051% while for Lactose is 0.0395%. For 425-500 particle size
(µm) the percentage retained is 0.0071% (MCC) while for Lactose is 0.0046%. For
355-425 the percentage retained is 0.1473% (MCC) while Lactose 4.5437%. For 150-355
is 6.6879% (MCC) while lactose 26.8064%. For 45-150 is 90.1897% (MCC) while lactose 68.3500%
. For <45 is 2.9629% (MCC) while lactose 0.2558%. From comparison of MCC and Lactose in the graph (Figure 3) we
can deduced that MCC has finer and smaller particle size as compared to Lactose
because the percentage retained of MCC in particle size (µm) >500, 355-425, 150-355
is lower than Lactose. This shown that particles of MCC is smaller that Lactose
so that the tendency to pass through the sieves hole is higher and make the
percentage retained is lower in particle size (µm) >500, 355-425, 150-355 sieves.
The total mass retained in sieves
for Lactose is 99.1775g. The mass of lactose when put in the sieves stack is 100g. There is lack of
0.8225g in total mass retained. While handling this experiment after sieving is
finished, we collect the total mass retained in each of the sieve but some of
the powder is split. This lead to reduce of total Lactose mass retained in the
sieve. The precaution can be made by more caution when handling this experiment
to avoid error.
Conclusion:
In conclusion, we can conclude that difference substance
have different of material properties such as Lactose and MCC. This difference
resulting in difference of size distribution. Differences material properties
required difference energy to reduce the particle size to the same size. This
experiment indicates that MCC has smaller in particle size than lactose powder.
Reference:
1. Patrick J. Sinko, Yashveer Singh. 2011. Martins Physical Pharmacy and
Pharmaceutical Pharmacy Sciences. Ed. ke6. China: Lippincott Williams &
Wilkins.
No comments:
Post a Comment