PRACTICAL 2 : SIEVING

OBJECTIVE

-determine the particle size distribution of a powder

-determine the size of a particle.

INTRODUCTION

A sieve analysis  is a practice or procedure used to assess the particle size distribution of a granular material. The size distribution is often of critical importance to the way the material performs in use. A sieve analysis can be performed on any type of non-organic or organic granular materials including sands, crushed rock, clays, granite, feldspars, coal, soil, a wide range of manufactured powders, grain and seeds, down to a minimum size depending on the exact method

APPARATUS AND MATERIAL

Lactose, microcrystalline cellulose (MCC), weighing machine, stack of sieves, mechanical sieve shaker

PROCEDURES

1. 100g of lactose was weighed

2. A 'sieve nest'  was prepared in ascending order and assigned appropriate sieve size

3. The lactose powder was put into the sieve.

4. Then, lactose powder was sieved for 20 minutes.

5. The results obtained was recorded and a graph on powder particle size distribution was built.

6. The process was repeated with MCC.

RESULT

GRAPH

DISCUSSION

From this experiment, there two materials that have been observed which are lactose and microcrystalline cellulose (MCC). The method used was sieving method,where we able to determine the particle size distribution. As a stack of sieves were prepared, the sieve that has larger opening size are placed above the ones that having smaller opening sizes . This means, the sieve that have diameter of aperture of 500 µm will be placed at the above followed by 425 µm, 300 µm, 150 µm, and 45 µm.

From the result obtained, the particle size of MCC falls in the range that less than 150 µm. At the same time, particle size for lactose also fall in the range of less than 150 µm. There are many factors that lead to this result. As the lactose and MCC are two different materials, so both of them have different physical properties. It seems that MCC has been affected more than lactose due to the physical vibration that applied on the particles since the hardness surface of particle is the one that contribute to the reduction of particle size. This experiment also cannot be considered accurate as the weight of lactose and MCC are not totally correct since there is still amount of powder left in the sieves after the process was carried out.  Besides that, some of powders are spilled out from the container since the machine is not closed correctly. This also affects to the result obtained.

So, before conducting this experiment, make sure the sieves are clean by using brush, because if many soil particles are stuck in the openings, this will affects the result of the experiments. The machine also must be set up correctly so that there is no problem occur during carrying out the process.

      

QUESTIONS

1)      What are the overall particles size of lactose and MCC?

The overall particle size range for MCC and lactose is 45µm, <45µm, between 45 and 150 µm , between 150 and 300 µm, between 300 and 425 µm, between 425 and 500 µm, and >500 µm.

2)      Are there any other methods that can be used to determine certain particle size?

The other methods that can be used to determine particle size are

a)      microscope methods

b)      coulter counter

c)      laser light scattering method

d)      dynamic light scattering method

e)      sedimentation method

3)      What are the importance of particle size in a certain formulation?

 Particle size in a certain formulation is important in achieving optimum production of efficacious medicines especially in pharmaceutical phase. It also can influence the bioavailability and activity of drug. For instance, it can influence segregation behaviour, the ease with which powder flows through the press and the compressibility of a formulation. This factor of formulation also can influence the disintegration and dissolution rate in the body cavity.

CONCLUSION

Based on the experiment, sieving process is one of the method to determine the size of particles.  The distribution of particles size are able to be analysed after conducting this experiment especially in achieving optimum production of efficacious medicines in pharmaceutical phase.

REFERRENCES

1. www.geog.ucl.ac.uk/about-the.../support...methods/.../sieving-method
2. http://www.pharma-excipients.com/micro-crystalline-cellulose.html
3. http://www.pharmaceutical-int.com/article/particle-size-is-important-particle-analysis-techniques.html
4. http://www.horiba.com/scientific/products/particle-characterization/applications/pharmaceuticals/