Experiment 4B - Particle Size and Shape Analysis using Microscope

Tittle: Particle size and shape analysis using microscope.

Date of experiment: 24^th November 2016

Objective:

1.      To analysis and interpret the particle size and shape with 5 different size of sands and powders (MCC, Lactose)

2.      To observe and compare the differences of the particles in size and shape from each sample.

Introduction:

            In order to achieve equivalent particle size and shape for drug (medicine) manufacturing, there are few methods can be used one of that is by using microscope. When using microscope, the particle size and shape can be seen clearly to ensure they in same size and shape. It is easier for industry pharmaceutical to manufacturing effective medicine for community. Powders also can be observed by using microscope, the particles have smaller size and shape to increase rate of dissolution.

Materials and apparatus:

Microscope compound, different size of sand particles and powders (MCC, Lactose).

Procedure:

      1.      Five different size of sand and powders are placed in a weighing boat.

    2.      The particles were analyzed to emphasis on the size and shape of the particles through the compound microscope.

     3.      Once the particles were observed microscopically the general shape for the particular material was determined.

RESULT – MICROSCOPIC VIEW

TYPE OF SANDS	MICROSCOPIC VIEW
150 MIC
355 MIC
500 MIC
850 MIC
VARIOUS SIZE
TYPE OF POWDERS	MICROSCOPIC VIEW
Microcrystalline Cellulose (MCC)
Lactose

DISCUSSION

Nowadays, particle size control of pharmaceutical manufacture of product quality becoming increasingly apparent in the pharmaceutical industry.

Particle size is a parameter having the dimension of length and defined by one or another of several arbitrary criteria such as:

1. The width of the smallest square opening, or the diameter of the smallest circular opening, through which the particle can pass

2. The diameter of a circle having an area equal to the maximum projected area of a particle

3. The diameter of a sphere whose volume is equal to that of the particle

4. The diameter of a sphere whose density and settling velocity are equal to those of the particle.

Several methods can be used in order to determine the particle size such as microscopy, sieving, sedimentation technique, Electrical sensing zone method- Coulter Counter, Laser Diffraction method and permeametry technique. The important of determine the size of particle are the release and dissolution of a drug. The release of drug that large in surface area much quicker because the size of drug is finer and particles dissolve quicker. Next, the dosage. The dosage of a particular drug might be altered if the particle size is too big or too small. In addition, if the particle sizes that aren't uniform may result in coagulation and improper dosages. Thus, improper dosages of certain drugs may result in severe reactions or even death in some cases.

In the experiment of Particle size and shape analysis using microscope, the particles that chosen to be observed are 5 different size of sand which are 150 mic, 315 mic, 500 mic, 850 mic and various siz and 2 type of powder which are lactose and MCC.

Compound Microscope is used in the experiment because compound microscope has sufficient magnification to allow adequate characterization of the smallest particles. The magnification which we used during this experiment set to be constant for all 7 samples which is 4x0.10 magnification. This is important so that we can compare the size and shape of the particle clearly and easily.

 Precaution when using the microscope is to ensure that the compound microscope is stable and is placed on a surface protected from vibration. From the experiment, we found out that the particles have different shape for different size of particles. The general size of each particles are very different from each other especially MCC and lactose which are smaller than the size of sand.

The particle size analysis can be done further by determine the diameter of the particle. The diameter of the particle can be calculated using 2 methods such as Feret's diameter or Martin's diameter. Feret's diameter is refers to the mean distance between two parallel tangents to the projected particle perimeter. Martin's diameter is the mean chord length of the projected particle perimeter. Advantages of this method are the particles can be examined individually.

CONCLUSION

From the observation in the experiment, we successfully analysis and interpret the particle size and shape with five different types of sands and powders (MCC, Lactose) through the compound microscope. We also successful observed and compared the differences of the particles in size and shape from each sample.

QUESTIONS FOR

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

There are several statistical methods which can be used to measure the diameter of a particle, such as Martin's diameter (dM), Ferret's diameter (dF), projected area and projected perimeter diameter (da or dp), sieve diameter (dS), volume diameter, longest dimension, and maximum chord.

Martin's diameter (dM) is the mean chord length of the projected particle perimeter, which can be considered as the boundary separating equal particle areas. The lines may be drawn in any direction which must be maintained constant for all image measurements. Martin’s diameter measures the chord of a particle and is useful for estimating the surface area of an irregular non-spherical particle. Ferret's diameter (dF) is the mean distance between two parallel tangents on opposite sides of the particle. This measure is used in the analysis of particle sizes, for example in microscopy, where it is applied to projections of a three-dimensional object on a 2D plane.

Next, projected area diameter (da) is the diameter of a circle having the same area to that of the projected image of a solid particle while projected perimeter diameter (dp) is based on the circle having the same circumference as the perimeter of the particle. Both of these methods are independent upon particle orientation. They only take into account of two dimensions of the particle, thus inaccurate for unsymmetrical particle.

A sieve diameter (dS) is defined as the width of the minimum square aperture through which the particle will pass. A common sizing device associated with this definition is a series of sieves made with square woven meshes. This diameter is frequently used in sieving experiment analysis. Volume diameter is a diameter of a sphere that has the same volume or surface area ratio as a particle of interest. Example of method that used this diameter is coulter counter machine.

In addition, longest dimension is a measured diameter equal to the maximum value of Ferret's diameter. Last but not least, 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 that can be used for every sample is Ferret’s and Martin’s diameter. This is because both methods can give us the average diameter over many different orientations of the particles. As the result, a mean diameter value for each particle can be obtained. Thus, these methods are more accurate in analyzing the samples that we used (in this case sands, lactose and MCC) compare to other methods. Other than that, considering the orientation and shape of the image, we can use the electron microscope since Ferret’s diameter accesses the three-dimensional image of particles.

Experiment 4A - Sieving

Title: Experiment 4 (Part A) - Sieving

Date of experiment: 24^th November 2016

Objectives

To determine the particle size and the size distribution of lactose and microcrystalline cellulose (MCC) by using sieve nest.

Introduction

A sieve, or sifter, is a device for separating wanted elements from unwanted material or for characterizing the particle size distribution of a sample. Sieving is a simple method for separating particles of different sizes. It is a generally utilized technique for particle size analysis and sort a large amount of particles to various size ranges. In this practical, sieving is used to determine the particle size and the size distribution of lactose and microcrystalline cellulose (MCC) by using sieve nest.

Apparatus and materials

Sieve nest, spatula, weighing boat, electronic balance, lactose and microcrystalline cellulose (MCC).

Procedure

     1.        100g lactose is weighed.

        

     2.        The sieve nest is prepared in descending order (largest diameter to the smallest, from top to bottom)

     3.        The powder is placed at the uppermost and the sieving process is allowed to proceed for 10 minutes.

     4.        Upon completion, the powder collected at every sieve is weighed, the particle size distribution is plotted in the form of histogram.

     5.        Steps 1-4 is repeated using lactose for 20 minutes.

     6.      The above process (steps 1-5) is then repeated using MCC.

RESULT

LACTOSE

SIZE OF THE SIEVE NEST (micrometre)	PARTICLE SIZE RANGE (micrometre)	LACTOSE
		10 MINUTES		20 MINUTES
		WEIGHT (g)	FREQUENCY (%)	WEIGHT (g)	FREQUENCY (%)
710	x < 710	16.6162	16.76	3.23	2.63
600	600 < x ≤ 710	44.2657	44.64	3.01	2.45
425	425 <  x ≤ 600	0.6282	0.63	2.70	2.20
300	300 < x ≤ 425	26.4944	26.72	18.15	14.79
150	150 < x ≤ 300	0.8332	0.84	23.79	19.39
53	53 < x ≤ 150	10.0649	10.14	54.00	44.01
50	50 < x ≤ 53	0.2128	0.21	12.57	10.24
<50	x ≤ 50	0.0501	0.05	5.26	4.28
TOTAL		99.1655	100.00	122.71	100.00

LACTOSE

10 MINUTES

20 MINUTES

MICROCRYSTALLINE CELLULOSE (MCC)

SIZE OF THE SIEVE NEST (micrometre)	PARTICLE SIZE RANGE (micrometre)	MICROCRYSTALLINE CELLULOSE (MCC)
		10 MINUTES		20 MINUTES
		WEIGHT (g)	FREQUENCY (%)	WEIGHT (g)	FREQUENCY (%)
710	x < 710	0.0126	0.02	2.8085	2.3
600	600 < x ≤ 710	0.1159	0.12	2.7503	2.25
425	425 <  x ≤ 600	0.1267	0.13	3.0490	2.49
300	300 < x ≤ 425	1.2817	1.29	3.9029	3.20
150	150 < x ≤ 300	0.4695	0.47	3.1775	2.60
53	53 < x ≤ 150	3.4532	3.48	5.4994	4.51
50	50 < x ≤ 53	60.1720	60.59	42.5846	34.90
<50	x ≤ 50	33.6766	33.91	58.2404	47.74
TOTAL		99.31	100.01	122.01	100.00

MICROCRYSTALLINE CELLULOSE (MCC)

10 MINUTES

20 MINUTES

DISCUSSION

            In this experiment, sieving method is used to determine the particle size distribution of lactose and microcrystalline cellulose (MCC). For each substance, different duration of sieving was used which were 10 minutes and 20 minutes. Sieving method or particularly called the sieving analysis technically involved the usage of sieve nests stacked together based on different range of diameter of the pores on the nest. The sieve nest arrangement in this experiment is descending from the biggest size on the top followed by the smallest sieve nest at the bottom. With the arrangement of the sieve nest, we placed the 710 micrometre aperture sieve nest on the topmost layer followed by the sieve nests with aperture of 600 micrometre, 425 micrometre, 300 micrometre, 150 micrometre, 53 micrometre, 50 micrometre and the sieve neat with the aperture <50 micrometre.

Throughout this discussion, we will compare the difference of the histogram obtained and how does the duration of sieving can affect the histogram pattern. From the data obtained, the weight of the lactose obtained after 10 minutes of sieving was 99.1655g and the pattern of the histogram plotted was randomly distributed with no significant shape which means the particles size distribution in lactose was random. The lactose particles was recorded to be the most in the sieve nest with 600 micrometre of diameter with a value of 44.2657g and the lowest amount was in the <50 micrometre sieve nest. To compare with the value obtained after 20 minutes of sieving, the weight of the lactose after 20 minutes of sieving is 122.01 and the pattern of the histogram plotted was bell shaped. The lactose particles were collected the most from the sieve nest with the smallest aperture of 53 micrometre which allowed particle size ranging from 53 micrometre < x ≤ 150 micrometre weighted 44.01g.

We can say that during the 10 minutes of sieving, the force of the sieving and the shorter period of time was not enough to disperse the particles size accordingly and the particles could not settle down passed the aperture of the sieve. Only after 20 minutes of sieving, did the lactose particles disperse accordingly by the size. As for the sieving of the Microcrystalline Cellulose (MCC), the weight obtained after 10 minutes of sieving was 99.31 and it showed a loss in the original mass of the MCC. The weight recorded for each particle size distribution presented no significant pattern and the histogram pattern of the MCC particle size distribution only can be seen after 20 minutes of sieving. The particle of the MCC after 10 minutes of sieving was collected the most in the sieve nest of aperture: 50 micrometre with particle ranging from 50 micrometer < x ≤ 53 micrometre.

After 20 minutes of sieving, the histogram obtained was right skewed and the particles size were collected the highest at the sieve nest with an aperture of < 50 micrometre. From both the histogram plotted in MCC sieving, the same explanation as in sieving of lactose, the force of the sieving and the shorter period of time was not enough to disperse the particles size accordingly and the particles could not settle down passed the aperture of the sieve. To compare between the particles size distribution of lactose and CCM, we can say that the particles of MCC is finer than the lactose based on the histogram plotted in which particles size of lactose particle is collected the most ranging from 53 micrometre < x ≤ 150 micrometre and the size of MCC collected was the most ranging x ≤ 50 micrometre.

Several errors have arisen in this experiment and caused the graphs obtained was not obeying the theory. The major error that can affect the mass of the powder collected is due to the unclean sieve nest. Supposedly the total weight of the lactose to be collected was 100 g but the obtained weight was exceeding in the 20 min of sieving for both lactose and MCC, and the weight of lactose and MCC was lesser than 100 g in the 10 minutes sieving process. Since the sieve nest is used by the previous group, even though same type of powders is used in the nest, there might be leftover of the powders being left behind in the sieve nest aperture. To overcome this, the sieve nest that is used must be cleaned by brushing the powders off the aperture before the experiment can be done.

Besides, error could also arise from the improper handling of the powder during the weighing process. To transfer the powder from the sieve nest could lead to loss in small amount of the powder due and also contamination from the foreign dust that will affect the weight of the powders. To prevent this, the sieve nests must be stacked tightly to the machine to avoid any leakage of the powder and also we used newspaper to collect the powders that escaped from the aperture to minimize error. Error could also occur from the exposure of the powder to the air since water vapour could cause the powders to aggregate and it will affect the weight of the powder measured.

CONCLUSION

            In the experiment, the particle size and the size distribution of lactose and microcrystalline cellulose (MCC) by using sieve nest successfully determined.

QUESTIONS EXPERIMENT 4 (SIEVING)

    1.      WHAT ARE THE AVERAGE PARTICLE SIZE FOR BOTH LACTOSE AND MCC?

The average particle size for MCC under 20 minutes is below 50 mic and the average particle size of MCC under 10 minutes is 50 mic. The average particle size for lactose under 20 minutes is 53 mic whereas the average particle size for lactose under 10 minutes is 600 mic.

    2.      WHAT OTHER METHODS CAN YOU USE TO DETERMINE THE SIZE OF PARTICLE?

Other methods that can be used to determine the size of particle are air elutriation analysis, photoanalysis, optical counting methods, electroresistance counting methods, sedimentation techniques, laser diffraction methods, laser obscuration time, acoustic spectroscopy and air pollution emissions measurements.

    3.      WHAT ARE THE IMPORTANCE OF PARTICLE SIZE IN A PHARMACEUTICAL FORMULATION?

The particle size is important as the size, distribution and shape of the particles can affect bulk properties, product performance, processability, stability and appearance of the end product. Furthermore, the link between particle size and product performance is well documented with regards to dissolution, absorption rates and content uniformity.

REFERENCES :

https://en.wikipedia.org/wiki/Particle-size_distribution

http://www.horiba.com/scientific/products/particle-characterization/applications/pharmaceuticals/