PRACTICAL 4 (PART B)

TITLE:

Particle Size and Shape Analysis Using Microscope

AIM:

To analyse and compare the shape and size of five different samples

INTRODUCTION:

The particle shape and size can be analysed by many methods. One of it is by using a microscope, which has been done in this experiment. This analysis can be used to determine the diameter, shape, and surface area of a particle. During the experiment, we were given different type of sand to be observed and analysed such as the size, shape and arrangement. We are using mixed size of sand, 150µ, 355µ, 500µ, and 850µ. We are also using lactose and MCC powder. In this experiment, we observe different sizes of particles under a microscope and sketch our observation.

EXPERIMENTAL METHOD:

MATERIAL AND APPARATUS:

Sands (150µ, 355µ, 500µ, 850µ, various size), Lactose powder, MCC powder, Microscope, Spatula, Glass slide, Cover slip

PROCEDURE:

1) 5 different types of sands with different sizes which are 150µ, 355µ, 500µ, 850µ and various sizes were analysed by using microscope, by observing the size and shape of given particle. The size and shape of 2 different types of powder, which are lactose powder and MCC powder were analysed too.
2) The samples were examined first by 4X10 magnification, followed by 10X10 magnification.
3) The particle shape is sketched and the overall particle shape of that material is stated.

RESULTS:

Sands with various size

Magnification: 4 x 100

Sands with 850µ

Magnification: 4 x 100

Sands with 500µ 

Magnification: 4 x 100

Sands with 355µ 

Magnification: 4 x 100

Sands with 150µ 

Magnification: 4 x 100

Lactose powder

Magnification: 4 x 100

MCC powder

Magnification: 4 x 100

QUESTIONS:

1. Explain in brief the various statistical methods that you can use to measure the diameter of a particle.

There are a few statistical methods to measure the diameter of a particle. Those methods are includes Martin’s diameter (M), Feret’s diameter (F), Projected area diameter (da or dp), longest dimension, perimeter dimension and maximum chord.

            Martin’s diameter (M) is the length of the line which bisects the particle image.  The lines may be drawn in any direction which must be maintained constant for all image measurements. Feret’s diameter (F) is the distance between two tangents on opposite sides of the particle, parallel to some fixed direction. Projected area diameter (da or dp)  is the diameter of a circle having the same area as the particle viewed normally to the plane surface on which the particle is at rest in a stable position. Longest dimension is a measured diameter equal to the maximum value of Feret's diameter. Perimeter diameter is the diameter of a circle having the same circumference as the perimeter of the particle. Maximum chord is a diameter equal to the maximum length of a line parallel to some fixed direction and limited by the contour of the particle.

2. State the best statistical method for each of the samples that you have analysed.

The best statistical method for each sample that has been analysed is Feret’s diameter and Martin’s diameter. Both methods will give the average diameter over many different orientations to produce a mean value for each particle diameter. This will give an average value of diameter in more orientation and giving an average diameter value which is more accurate.

DISCUSSION:

            Optimum production of efficacious medicine is significantly affected by the size, shape and dimension of particulates. Since solid particle is often considered to approximate to a sphere and can be characterised by the determination of its diameter. More than one dimension could be generated for a given irregular particle, such as projected perimeter diameter and projected area diameter. Feret’s and Martin’s diameters produce a mean value for each particle diameter.  Feret’s diameter refers to the mean distance between 2 parallel tangents to the projected particle perimeter. Martin’s diameter is the mean chord length of the projected particle perimeter which can be considered as the boundary separate equal particle areas.

There are various methods to determine particle size and shape. A right method should be chose to analyse the particles. Firstly, the nature of material that has to be analysed should be consider. On the other hand, the cost specific requirements and time restriction should be taken into consideration. Microscope is among the excellent technique as operator could able to examine each particle individually. This is a relative cheap method to be use. However, it is not suitable for quality control as operator need to elaborate sample preparation and slow. The operator would experience rapid fatigue and it may cause variability to analysis the size of particle in the same sample. Operator bias may present. There is also lack of information on 3D shape in this method.

The microscope used in this experiment is light microscope and the magnification used throughout the experiment is 4x for the 7 sample analysed. The samples are dispersed evenly to prevent the presence of agglomeration. From the experiment, the size of material used in ascending order is MCC, lactose, 150µm, 355µm, 500µm, 850µm and lastly various size. The general shape for sands are irregular shape and for MCC and lactose are in cylindrical shape.

The important technique throughout the experiment includes operator should take a very least amount of particles to analysed under microscope to prevent agglomeration and ensure the shape and size to be seen clearly. While handling the microscope, correct techniques should applied to ensure microscope in good condition. Slides should be clean properly so that smear does not present and affect the observation.

CONCLUSION:

The size and shape of a particle can be analysed through microscopy analysis. Different types of particles have different sizes and shapes. In this experiment, it can be concluded that the size and shape of the particles are irregular and asymmetrical. 

REFERENCE:

1) Carlton, R. A.   2011.    Pharmaceutical Microscopy. Springer Science & Business Media.

2) Stanley-Wood, N. & Lines, R. W.   1992.    Particle Size Analysis. Royal society of chemistry.

3) Rolston Gordon Communications, 2001. Microscopy and Analysis.