Particle Size Distribution of a powder- Sieving Method

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BACKGROUND

Pharmaceutical powders ideally should contain particles of one size which is not possible by any size reduction method. At least, the powders should contain narrow size distribution. Therefore, these materials are controlled to meet official specifications. For this evaluation, sieving method is used. The basic principle involved in this method is size separation using standard sieves or screens.¹

Size separation is a unit operation that involves the separation of various sizes of particles into two or more portions by means of screening surfaces.²

Sieving method directly gives weight distribution analysis. From the data d_sieve can be calculated. Sieve diameter is defined as the diameter of a sphere that passes through the sieve aperture as the asymmetric particle.

The average particle diameter of a powder d _average is calculated using the following equation.³

Aim: The aim of the experiment were to determine the particle size weight distribution of a given sample by sieving method and to determine average particle diameter of a powder, d sieve.

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REQUIREMENTS

Apparatus: Standard sieves set

Mechanical sieve shaker

Weighing balance

Chemicals: Calcium carbonate

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PROCEDURE

Select standard sieves set consists of various sizes (10, 22, 44, 60, 85, 100 and 120). Arrange the sieves in such a manner that coarsest remains at the top and finest at the bottom. Keep the pan below the sieves set. Weigh hundred grams of given sample.  
Place the sample on the coarsest sieve and the lid. Fix the above sieves set on mechanical shaker and clamp tightly.
Shake the mechanical shaker for 30 minutes. After 30 minutes, retain the sample on each sieve is collected into a paper. Weigh all samples. Record the weights retain on each sieve in table against corresponding sieve number. Analyze the data for normal weight distribution pattern. Draw a plot by taking mean size of opening on X- axis and percent weight retained on y- axis. Calculate the average particle size.

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CONCLUSION

The average particle size was ______________.

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REFERENCES

1. Subrahmanyam CVS, Setty JT, Suresh S. Laboratory manual of pharmaceutical engineering (Unit operations). Delhi Vallabh Publications.
   
2. Pharmaceutical Engineering by Sanbamurty K. (New Age International, New Delhi)Cooper and Gunn’s Tutorial Pharmacy Edited by Carter SJ. (CBS Publishers, Delhi)
   
3. Pharmaceutical Dosage forms by Aulton. (Churchill Livingstone, Edinburg).