Aim: To determine the average particle size and find out their distribution pattern for the given granules by sieve analysis method.
Principle:
Sieve method gives seive diameter is defined as the diameter of the sphere that possess through the sieve aperture as the asymmetric particle sieve method directly give weight distribution. Particles having size range from 50 and 1500rpm are estimated by sieving method. In this method, the size is expressed as d sieve.
Size separation: It is a unit operation that involves the separation of various sizes of particles into two or more portions by means of screening surfaces. It is also known as sieving, sifting, classifying or screening.
Size Diameter: It is define as the diameter of sphere that passes through the sieve apparatus as the asymmetric particles.
Standard sieves of different mesh numbers are available commercially as per the specifications of IP and USP as given below.
Designations and Dimensions of IP specification sieves
| sieve num ber |
Aperature size Micrometer |
Sieve Number |
Aperture size Micrometer |
|
|---|---|---|---|---|
| 10 | 1700 | 44 | 355 | |
| 12 | 1400 | 60 | 250 | |
| 16 | 1000 | 85 | 180 | |
| 22 | 710 | 100 | 150 | |
| 25 | 600 | 120 | 125 | |
| 30 | 500 | 150 | 106 | |
| 36 | 425 | 170 | 90 | |
Advantages of Sieving method
- it is in expensive, sample and rapid with reproducible results.
- Sieving method is useful when particles are having size range between 50and 1500μm
Disadvantages of Sieving method
- Lower limit of the particle size is 50μm.
- If the powder is not dry,apertures becoming clogged with particles leading to improper sieving
- During shaking, attrition occurs causing size reduction of particles. this leads to errors in estimation.
Application:
Sieving method finds application in dosage form development of tablets and capsules. Normally 15% of fine powder (passed through mesh 100) should be granulated material and achieved good compacting in tableting.
Procedure:
- Standard sieves set is selected (sieve: 10, 22, 36, 44, 65, 80, 100, 120,) arrange them in such manner that the coarsest remains at the top and the finest at the bottom.
- Weigh approximately 100g of sample place the sample on the coarsest sieve no:10.
- Fix the above sieves set on sieves shaker and shaken for 20 minutes.
- Collect the sample retained on each sieve into a paper, weigh all the sample.
- Report the weights retained on each sieve in the table against corresponding sieve number.
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