Title : Sieving

Objective

To determine the particle size distribution of the powder material with respect to the size of the solid particles.

Introduction

A sieve is a mesh strainer used to separate lumps and clumps from the fine material Or an instrument with a meshed or perforated bottom, used for separating coarse from fine parts of loose matter,

A sieve test is performed by first assembling a stack of interlocking sieves. In this stack the sieve with the largest openings is at the top each lower sieve will have a smaller opening than the one above it.. A pre-weighed sample of the material to be tested is placed in the top sieve. This sieve stack is the shaken until all all the material has either been retained on a sieve or passed through. The material retained in each sieve is weighed and compared to the weight on the other sieves. A sieve test analysis or distribution is calculated which shows the proportion of each particle size category in the sample

Test sieves usually have a round frame, in sizes that range from 3inches to 18 inches (and the metric equivalents) in diameter. Woven wire mesh with proscribed openings is the most common test sieve media, This is followed by perforated plate andelectroformed material. These are the most common media used for sieve analysis.

Material
glucose powder and micro crystalline cellulose (MCC)  powder

Apparatus
"sieve nest" machine

method

1. Consider 100g of lactose

2. Prepare a 'sieve nest' in ascending order and assigned appropriate sieve size

3. Put the powder into the sieve lactosa.

4. Sieve for 20 minutes.

5. After completing consider the results obtained and build a graph on powder particle size distribution.

6. Repeat the process with MCC

Result

sieve	Glucose (g)	MCC (g)
1	0.0162	3.5x10-3
2	0.0267	4.3x10-3
3	0.0160	0.0787
4	30.5684	4.9485
5	57.5150	51.8688
6	11.1436	42.1931

Discussion

A sieve test is performed by first assembling a stack of interlocking sieves. In this stack the sieve with the largest openings is at the top each lower sieve will have a smaller opening than the one above it.. A pre-weighed sample of the material to be tested is placed in the top sieve. This sieve stack is the shaken until all the material has either been retained on a sieve or passed through. The material retained in each sieve is weighed and compared to the weight on the other sieves.

The data can match sieve results for narrow and wide distributions, ranging from 30 micron to 30 mm. This is an essential point when replacing the traditional sieving technique with a faster and more precise method, but without changing the product specifications.

The ability to analyse the particle shape is important for the detection of aggregates. It is also required for the quality control of some types of particle which must consist of cubic or elongated particles. Figure shows a plot of particle shape as described by the aspect ratio calculation (x-axis) vs. % under on the y-axis.

It is also possible to display the particle size distribution as a histogram including the upper and lower specification ranges, as shown in    

          The graph show that the distribution of size particle is different. Size 2.5 mm is dominately for both powder which are glucose and lactose while size of 0.5 is the least. But in this experiment, there are some error due dust and other powder that effect of the weight.

Conclusions

 By the using of sieve nest, we can know that the distribution of particle size which is totally different that will effect the stability of the drug that we want to produce.

References

1)       Aulton, M.E. 2002. Pharmaceutics: The Science of Dosage form Design. Edinburgh Churchill Livingstone

2)      Banker, G.S & Rhodes, C.T. 2000. Modern Pharmaceutics. Ed. Ke-2. New York. Marcel Dekker.