PRACTICAL 4 (PART B): PARTICLE SIZE AND SHAPE ANALYSIS USING MICROSCOPE

Title :

Particle size and shape analysis using microscope

Objectives :

1.         To analyze and interpret the size and shape of particles with five different samples.

2.         To observe and compare the different size of particles under microscope for each samples.

Apparatus :

Microscope, slide, cover slip, spatula

Chemicals :

Sands (150µ, 350µ, 500µ, 850µ, mixed), MMC, lactose

Introduction:

   Particles size analysis is important for drugs efficacy in pharmaceutical. In achieving optimum production of efficacious medicines, the dimensions of particulate solids is one of the dominant factor. The smaller the total surface area exposed, the higher the rate of reaction. Microscopy is a method that allows the individual particles to be observed and measured. A digital camera with a fixed magnification lens is used to take a picture of a sparse layer of representative particles distributed on the microscope slide. In this experiment, we use the microscopy method to observe the size and shapes of the sand particles. Each sand particles are differ and vary from each other. In this experiment, there are 150µ, 350µ, 500µ, 850µ and mixed) and powders (MMC and lactose) used. The particles size and shaped is observed.

Procedure:

1. A microscope was used to analyse 5 different types of sands which are 850mic, 500mic, 350mic, 150mic, various sizes, and powders (MCC and lactose).

2. The particles observed microscopically were then sketched and the general shapes for that particular material were determined.

3. The magnification used in sketching the materials was fixed.

Results:

150 mic

500 mic

850 mic

Lactose

MCC

Mixed sand

Discussion:

  Particles analysis is important for drugs efficacy of drugs. The rate of dissolution is influenced by the particles size. The bigger the particle size, the slower the rate of dissolution of particles. Smaller particles have bigger total surface area exposed that will increase the rate of dissolution of particles. For the rough and coarse particles, the particles will be harder to dissolve in solution due to smaller surface area exposed.

 There are various type of methods to observe the size of particles. In this experiment, there are 850µ, 500µ, 350µ, 150µ and mixture of sands as well as 2 powders, lactose and MCC. This experiment is carried out using a light microscope to observe the size of particles.

  The results are observed from microscope using naked eyes. The results show that every sand particles have different sizes. The size of particles vary from each other. The size of powder particles is smaller than sand. The size of MCC particles is bigger than lactose. 

 There are some precautions that must be taken. First, goggles and gloves must be worn. This can prevent the chemicals from spilling to naked eyes and skin which some of the chemicals are hazardous. Besides that, the microscope should be adjusted until the clearest images is obtained to obtain the most accurate result.

Question:

1. There are two types of methods which can determine the       particles size. The methods are Feret and Martin diameter and        histogram. Martin’s diameter is defined as averaged cord length of a particles which equally divides the projected area. Feret’s diameter is averaged distance between pairs of parallel tangents to the projected outline of the particles. The histogram shows the distribution of sizes of the particles in different size range.

 Martin’s and Feret’s diameter of a particles depend on the orientation of particles which is made by the measurement. A large number of randomly sampled particles are needed to obtain a significant measurement at a fixed orientation. Usually this method is used in optical microscope. Histogram will show the distribution of different sizes of particles in normal distribution, positive-skewed or bimodal distribution.

2. Martin;s and Feret’s diameter is the most suitable methods to identify the particle sizes because in this experiment involve the use of optical microscope. The size of particles can be determined through Martin’s and Feret’s diameter.

Conclusion:

The size of the sand particles (850mic, 500mic, 350mic, 150mic, various sizes) and powders (MCC and lactose) are observed and compared. The size of MCC particles is bigger than the size of lactose particles. However, all the particles shapes are irregular and different sizes. Therefore, particles sizes examination is important for pharmaceutical as it will affect drugs efficacy.

Reference :

1.      Reider, Ralf, and I-Wei Chen. Ceramics Science and Technology: Vol. 3. Weinheim: Wiley-VCH Verlag GmbH, 2011. Print.

2.      Augsburger, Larry L. Pharmaceutical Dosage Forms Tablets. 3.rd ed. New York: Informa Healthcare, 2008. Print. 

3.       A. T. Florence and D. Attwood, Physicochemical Principals of Pharmacy, 2nd Edition, The Macmillan Press Ltd.