TITLE
Particle Size and Shape Analysis Using
Microscope
DATE
19th of November 2015
OBJECTIVES
i. To analyze the particle size of different
types of samples
ii. To investigate the general shape of
particles of different samples
INTRODUCTION
Particle size analysis is a method
used to determine the size range and the average or the mean size of the
particles in a powder or liquid samples. There are various methods used to
determine the particle size and analyze the shape. One of the most reliable
techniques to characterize particle size is by the use of microscope and image
analysis. In this experiment, various
types of sands and powders (MCC, lactose) are examined under microscope and
their shape and size are recorded and compared.
The
particle size distribution of active ingredients and excipients is an important
physical characteristic of the materials used to create pharmaceutical
products. The size, distribution and shape of the particles can affect bulk
properties, product performance, process ability, stability and appearance of
the end product. Powders with different particle sizes have different flow and
compaction properties. This will alter the volumes of the powder during the
encapsulation or tablet compression events.
The determination of suitable
particle size and shape analysis is important in achieving optimum production
of efficacious medicines. The particle size can
have considerable importance in a number of industries including the chemical,
mining, forestry, agriculture, nutrition, pharmaceutical, energy, and aggregate
industries.
APPARATUS
 |
| Weighing Boat |
 |
| Cover Slip |
 |
| Glass Slides |
 |
| Light Microscope |
 |
| Spatula |
MATERIALS
 |
Five different types of sand ( 150 mic, 355mic,
500mic, 850mic and various size )
|
PROCEDURES
1. Microscope was set up.
2. Five
different sand particles were labeled with A, B, C, D and E.
3. A small
amount of sample A was taken out from the container prepared in the laboratory
and
4. Sample A was then slowly and carefully being
placed on the glass slide.
5. Before covering sample A with cover slip,
sample A was spread evenly and fairly flat on the
6. The sample was then examined under microscope
with a magnification of 4x10 and
of 10 x10.
of 10 x10.
7. Particle size of sample A was
recorded and the general shape of the particles was drawn.
8. The
experiment was repeated by using samples B, C, D, E, MCC and lactose.
OBSERVATION
Size of sand: 150 µm
(The sand particles have irregular
shape.)
a) 4
X 10 magnification
b) 10 X 10 magnification
Size of sand: 355 µm
(The particles size is larger than 150 µm sand. The shape of the particles is
irregular and almost the same size.)
a) 4 X 10 magnification
b) 10 X 10 magnification
Size of sand: 500 µm
(The particles size is larger than 355
µm sand, irregular shape and also uneven size.)
a)
4 X 10 magnification
b)
10 X 10 magnification
Size of sand: 850 µm
(The particles are largest among the
seven samples as the diameter of the sand is the longest. The size of particles
displayed is not equally the same. The shape of the particles is irregular and
without a defined shape.)
a) 4 X 10 magnification
b)
10 X 10 magnification
Size of various sands
(It contains of different type of sand,
hence all the particles have different size. Most of them have irregular shape
with different number of edges and sides.)
a)
4 X 10 magnification
b) 10 X 10 magnification
Lactose
(Among seven samples, lactose has the
smallest size of particles. Some of the particles are rounded in shape whereas
some of them are irregular size.)
a)
4 X 10 magnification
b)
10 X 10 magnification
MCC
(The size of particles is a bit larger
than lactose particle. It is in the form of discrete and irregular size.)
a) 4 X 10 magnification
b) 10 X 10 magnification
QUESTIONS
- Explain
in brief the various statistical methods that you can use to measure the
diameter of a particle.
One of the statistical methods in
measuring the diameter of a particle is the horizontal and vertical Feret’s diameters.
It is the size encountered in classical analysis which denoted as Dfh
(horizontal) and Dfv (vertical). Feret’s diameters are defined as
the distance between parallel tangents. Feret’s diameters are easy to measure
and relate intuitively to characteristic dimension that may be vital in sieving
process. Besides, another effective method is Martin’s diameter which it is
denoted by Dm. It is defined as the length of the chord through the
centroid which bisects the area of the particle. Both Feret’s diameters and
Martin’s diameter can be applied to the same particle at the same time.
Moreover, the next method that can
also be used in measuring the particle diameter is the projected area diameter.
It is denoted as Dp and defined as the diameter of a circle having
the same area as the particle. This measure is unique and it does not depend on
the orientation of the particle as it is presented in the field of view. The
definition of Dp needs that the area of the particle profile be
computed.
Method of length, breadth and
thickness as measures of particle size can be considered during measurement.
The measurement of size is the limiting dimensions of a particle in decreasing
order of magnitude which are length (L), breadth (B) and thickness (T). The
thickness is defined as the minimum distance between two parallel plane tangent
to the opposite surface. The breadth is defined as the minimum distance between
parallel planes perpendicular to the planes defining the thickness. The length
is the distance between parallel planes perpendicular to both sets of planes
defining the thickness and breadth. These planes are tangent to opposite
surface.
- State
the best statistical method of each of the samples that you have analysed.
Hence, the best statistical method
that be chosen for measurement of particle size is Feret’s and Martin’s method.
It is due to the horizontal diameter, vertical diameter and also the length of
the chord of the particle can be obtained and the average values of diameter
can be calculated. Therefore, a more accurate result of size of particle can be
obtained.
DISCUSSION
In this experiment, the skill of
microscopy is applied in examining the size and general shape of the samples.
The samples used in the experiment are 150 micron sands, 355 micron sands, 500
micron sands, 850 micron sands, various sizes of sands, lactose powder and MCC
powder. All the samples are examined under light microscope by using the
magnification of 4 x
10 and followed by magnification of 10 x10. Light microscope is used instead of
transmission electron microscope and scanning electron microscope in this
experiment because light microscope is suitable to examine particle size ranges
from 0.1 micrometer to 100 nanometers.
While examining the sample under
microscope, the examiner has to sketch out the general shape and size of the
sample. After that, the size and shape of different samples can be differentiated
through the sketching. Based on the observations, lactose powder has the
smallest particle size among the samples. Through
the sketching, every sample each has different shapes and all with irregular
shape. The general shape of particles ranges from very angular, angular,
sub-angular, sub-rounded, rounded to well rounded. The particles shape of all
samples are not regular and constant.
In the experiment, Feret’s diameter
and Martin’s diameter are the best methods to be used in particle size analysis.
Feret’s diameter is the mean distance between two parallel tangents to the
projected particle perimeter while Martin’s diameter is the mean chord length
of the projected particle perimeter. These two methods are dependent on the
orientation and shape of particles. Besides, Feret’s diameter and Martin’s
diameter are the statistical diameters which are averaged over different
orientations to produce a mean value for each particle diameter. Hence, this
can increase the accuracy of the results obtained.
The experiment is conducted in a
non-windy environment and the tables are required to be covered with newspaper
to prevent the sands and powders from spreading all around. This is to maintain
the cleanliness of the laboratory. Besides that, goggles should be used while
conducting the experiment to prevent the samples from getting into the eyes.
Every sample is to be applied on the cover slip with a thin layer to avoid
agglomeration (solid particles stick together) in order to obtain a better and
accurate observation.
CONCLUSION
Each of the particles that have being examined under microscope is
different in their sizes and general shapes.
Most particles have irregular and asymmetrical shape. Lactose and MCC
powders are having a smaller size compared to the other five types of sand.
This implies that granulation is important to ensure that flow ability of the
drug can be achieved.
REFERENCES
1. Michael
E.Aulton, 2007, Aulton's Pharmaceutics The Design And Manufacture Of Medicines, Third Edition, Churchill
Livingstone Elsevier (page 122-134).
2. Essentials of Particle Size Analysis, Mar 14,
2013. Retrieved from: http://www.slideshare.net/HORIBA/essentials-of-particle-size-analysis
4. Patrick J. Sinko & Yashveer Singh, 2011, Martin’s Physical Pharmacy and Pharmaceutical
Sciences. 6th edition, Lippincott Williams & Wilkins, a Wolters Kulwer business
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