Part A: Particle
Size analysis using Sieving Method
OBJECTIVES
To determine the
particle size of lactose and microcrystalline cellulose (MCC).
To classify and
differentiate the powder based on the diameter of the powder particles.
To identify the size
distribution of lactose and microcrystalline cellulose (MCC)
DATE OF EXPERIMENT
16th
November 2015
INTRODUCTION
A
test sieve is an instrument which is used for the measurement of particle size.
In its most common form it consists of a woven wire screen, with square
apertures, rigidly mounted in a shallow cylindrical metal frame. For coarse
sieving a perforated plate screen with square or round holes may be used in
place of wire mesh. Square hole perforated plate sieves range down to 4mm and
round hole sieves down to 1mm aperture.
A
sieve test is performed by first assembling a stack of interlocking sieves. In
this stack, the sieve with the largest opening is at the top. Each lower sieve
will have a smaller opening than the one on the above.
The
materials which are tested in this experiment are lactose and microcrystalline
cellulose (MCC). The lactose is first weighed and is poured into the sieve nest
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 celluluose. The overall results are then presented
in histograms.
LIST OF
MATERIALS
Microcrystalline cellulose (MCC), Lactose
LIST OF
APPARATUS
Mechanical sieve, sieve
nests, large weighing boats, spatula, electronic balance, newspaper
EXPERIMENTAL
METHOD
1. 100
g of lactose is weighed.
2. The
sieve nest is prepared in descending order (largest diameter to the smallest,
from top to bottom).
3. The
powders are placed at the uppermost sieve and allow the sieving process to
proceed for 15 minutes.
4. Upon
completion, the powder collected is weighted at every sieve and the particle
size distribution is plotted in the form of histogram.
5. The
above process is repeated using MCC.
RESULTS
Lactose
|
|||||
Diameter of sieve
nest (μm)
|
50
|
150
|
200
|
425
|
500
|
Weight (g)
|
38.6768
|
0.1488
|
60.9122
|
0.0092
|
0.0218
|
MCC
|
||||||
Diameter of sieve
nest (μm)
|
<53
|
53
|
150
|
200
|
300
|
500
|
Weight (g)
|
17.5855
|
76.8885
|
3.3547
|
1.8236
|
0.2216
|
0.1261
|
QUESTIONS
1. What are the average particle size
for lactose and MCC?
The average particle size of lactose is
between 50 µm to 200 µm and the average particle size of MCC is between 50µm to
150µm.
2. What other methods can you use to
determine the size of particle?
The other methods to determine the
size of particles are surface area measurement, sedimentation, electron
microscope analysis, Coulter counter, laser light scattering technique, dynamic
light scattering technique and optical and electrical sensing zone method.
3. What are the importances of
particle size in a pharmaceutical formulation?
For
the pharmaceutical industry, particle size impacts products as an influence on
drug performance. Particle size of the active
pharmaceutical ingredient (API) and inert excipients are to be considered in
pre-formulation, design of drug delivery system as it is influencing the
proceessability, stability, bioavailability and efficacy of drug delivery
system. Particle size is having a pronounced effect on the absorption of drugs
with low aqueous solubility for the solid dosage form. Smaller particle size
has higher absorption compared to bigger particle size for the conventional
solid dosage forms such as tablets that are administered orally for local and
systemic action. In the other hand, the particle size of disintegrants like
starch influences the disintegration time of the tablets as starch grains with
large particle size are more efficient disintegrants compared to the smaller
one. Furthermore, the efficacy of lubricant is also influenced by the particle
size and lubricants that having a particle size of 60-100 mesh are used most
often. For insoluble drugs, the particle
size of the filler influenced the dissolution rate and affect on the solubility
of the drug. Syringeability and injectability properties of a parenteral
suspension are closely related to the particle characteristics of the
parenteral suspension. The rate of reconstitution from a drug powder to form
aqueous solution/suspension is influenced by the particle size. The particle
size of the dispersed phase should be below 10um in order to minimize pain and
tissue irritation.
DISCUSSION
Sieving is one of the oldest methods of classifying
powders and granules by particle size distribution. The sieving will sort the
particle by their intermediate size dimension when sieve using a woven sieve
cloth. The particles larger than 75µm is sieved with mechanical sieving whereas
for smaller particles, the light weight provides insufficient force during
sieving and this will cause the particles to stick together and the particles
expected to pass through the sieve will be retained. Sieving is a method of
choice to classify coarser grades of single powders or granules in the
pharmaceutical field.
In
this experiment, the particle size distribution of lactose and are
microcrystalline cellulose (MCC) are being observed. The method used to determine their particle size
distribution was sieving method or sieve analysis. A sieve nest is used to
determine the article size distribution. The sieve
nest is arranged in descending order from top to bottom which is from largest
diameter to smallest diameter. The sieve
that have diameter of aperture of 500 µm
will be placed at the top followed by 425 µm, 200 µm, 150 µm, and 50 µm. The
coarsest sieve was loaded with the lactose powder and it is operated for
mechanical vibration for 20 minutes. The procedures are the same for the
microcrystalline cellulose (MCC).
In
this experiment, the particle size of lactose is measured based on the principle
that the particle cannot pass through the sieve due to larger size particle
than the sieve. Based on the results obtained, the particle size of lactose is
mostly in between 200 µm and 425 µm as 60.91g of lactose is collected in this sieve followed
by particle size less than 50 µm as 38.68g of lactose is collected at the most
bottom sieve. In microcrystalline cellulose (MCC), the powder is mostly
collected in the 53 µm sieve with 76.89g
and we can assume that microcrystalline cellulose (MCC) have particle size is
in between 53 µm and 150 µm follow by less than 53 µm as 17.58g of microcrystalline
cellulose (MCC) is collected. Comparing both lactose and microcrystalline
cellulose (MCC), we can deduct that microcrystalline cellulose (MCC) have smaller particle size and finer than
lactose.
The initial total weight
of lactose and microcrystalline cellulose (MCC) is both 100g but by
the end of experiment, the weight of lactose is 94.9g whereas microcrystalline
cellulose (MCC) remains 100g. This clearly indicates that some of the lactose
powder is lost during the lab and error occurs. One
is when transferring of lactose and microcrystalline cellulose (MCC)
from the weighing boat into the sieve and after 20 minutes of mechanical
vibration, the transferring of the powder back into the weighing boat for
weighing. During the process of transferring, some of the powder is still
preset either in the sieve or weighing boat. This explains why the final weight
of the lactose powder is not exactly 100g. The second error that occurs during
the lab is the sieve nest is not covered tightly due to the machine
malfunction. . Some of the powder may spill out from the container as the
machine is not closed tightly. In this condition, the vibration of the machine
may be irregular and this will affect the separation of powder in the sieve
nest. Thus, error occurs. The powders are light weight particles. Thus, when
exposed to air, it may evaporate of carried by water vapour into the air
causing loss of weight. The mass will not be accurate. Before the experiment, the sieves are cleaned
using a brush to remove any powder from the previous experiment. The machine
needs to be sealed tightly to prevent error.
CONCLUSION
Most particles
size of lactose are in the range of 0 - 49µm followed by range of 151 – 200µm.
While as for MCC, most particles size are in the range of 0 - 52µm followed by 53
µm. This shows that most particles in MCC is smaller than those of lactose.
REFERENCE
Martin, A. 2011. Physcial
Pharmacy: Physical Chemistry Principles in Pharmaceutical Sciences. Edisi
ke-6. Philadelphia: Lippincott Williams & Wilkins.
Chang, R. &
Goldsby, K. A. 2014. Chemistry. Edisi ke-11. New York: McGraw- Hill
Education.
This comment has been removed by the author.
ReplyDeleteResearch Lab Equipment
ReplyDelete