Official Standards of Powders.

 Official Standards of Powders.

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• lndian Pharmacopoeia has prescribed standards for powders for pharmaceutical purposes. 

• Accordingly, degree of coarseness or fineness is expressed with reference to the nominal aperture size of sieve through which powder is able to pass. 

• The IP 1996 specifies five grades of powders.

Sr. No.	Grade of Powder	Sieve through which all particles must pass	Nominal Mesh Aperture Size	Sieve through which 40% Particles pass	Nominal Mesh aperture size.
1	Coarse Powder	10	1.7 mm	44	355 µm
2	Moderately Coarse Powder	22	710 µm	60	250 µm
3	Moderately Fine Powder	44	355 µm	85	180 µm
4	Fine Powder	85	180 µm	--	--
5	Very Fine Powder	120	125 µm	--	--

A) Coarse Powder:

• A powder, all the particles of which pass through a sieve with nominal mesh aperture of 1.70 mm (Sieve No. 10 ) and not more than 40% pass through nominal mesh aperture of 355 µm (Sieve No. 44) is called a Coarse Powder.

B) Moderately Coarse Powder: 

• A powder, all the particles of which pass through a sieve with nominal mesh aperture of 710 µm (Sieve No. 22) and not more than 40% pass through nominal mesh aperture of 250 µm (Sieve No. 60) is called a Moderately Coarse Powder.

C) Moderately Fine Powder:

• A powder, all the particles of which pass through a sieve with nominal mesh aperture of 355 µm (Sieve No. 44) and not more than 40% pass through nominal mesh aperture of 180 µm (Sieve No. 85) is called a Moderately Fine Powder.

D) Fine Powder: 

• A powder, all the particles of which pass through a sieve with nominal mesh aperture of 180 µm (Sieve No. 85) is called a Fine Powder.

E) Very Fine Powder:

• A powder, all the particles of which pass through a sieve with nominal mesh aperture of 125 µm (Sieve No. 120) is called a Fine Powder.

Commonly Asked Question.

1. Write a short note on official grades of pharmaceutical powders.