Title
Analysis of shape and
size of particle using microscope
Aim
To observe the shape
and size of particles of five different samples provided by using a microscope.
Introduction
1. Samples prepared to
be observed using light microscope need to be dispersed adequately. This is to
ensure there is no particles agglomeration.
2. Size analysis by
light microscope is carried out on the 2D particles images. The images are
analysed according to the desired equivalent diameter.
3. By using microscopic
observation, measurements and data for the calculation of particle size and
shape can be determined easily and directly from each particle profile.
4. This method is
relatively inexpensive.
5. Particle size, size
distribution, and qualitative or quantitative shape information can easily and
rapidly be obtained simultaneously.
6. Particle length and
width characterization, can take less than 15 minutes.
7. The equipment is
versatile and flexible in measurements and calculations.
Experimental
procedure
1. Five different
samples (150 mic, 355 mic, 500 mic, 850 mic and various sizes) of sands were
prepared on five different glass slides each.
2. All the prepared
slides were observed using microscope. Magnification of x10 was used in every
sample.
3. The shape and size
of particles of the sands were determined and drawn.
Results
and Calculation
Overall shape of the
sand particles is irregular shape. The sketches of the particle images are as
shown in the table above.
Discussions
1. Briefly describe all statistical
methods that can be used to measure the diameter of a particle.
As most powders contain particles with a range of
different equivalent diameters, therefore it would be easier if we could
describe a size distribution which can be broken down into different size
ranges. A histogram can be used to present an interpretation of the particle
size distribution. From this, the percentage of particles having a given
equivalent diameter can be determined. There are different statistical methods
that can be used to measure the particle diameter. The methods are mean
particle sizes, arithmetic means and geometric means.
In mean particle size
method, the mean, median and mode of particle population are all used in
determining central tendency. The mean diameter can only be obtained from a
complete particle size distribution. From an incomplete particle size
distribution, the mode and the median can be obtained.
Arithmetic means use
summation of a particular parameter for all single particles in a sample and
the achieved value is divided by the total number of particles.
Geometric means is used
when not all powder samples show an arithmetic distribution of particle sizes. Some
particles follow the log-normal distribution.
2. For each sample that you have observed,
choose the best statistical method that you have used.
Observation of sand
particles – mean particle sizes method
Conclusion
The availability of the
instruments in the laboratory would influence the selection of a particle size
analysis method. The powder properties and the type of information required are
said to govern the limitations on the choice of method.
References
2. Aulton M.E. 2007.
Pharmaceutics : The Design and Manufacture of Medicines. Edinburgh Churchill
Livingstone.
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