Official standards of powders, sieves and size separation

Official standards of powders,  sieves and size separation

In the pharmaceutical industry, maintaining the quality and consistency of drug formulations is paramount. One of the critical processes that ensure this consistency is size separation, which involves categorizing particles based on their size. This process is governed by official standards that dictate the specifications for powders and sieves used in pharmaceutical manufacturing. Understanding these standards is essential for pharmaceutical professionals to ensure the efficacy, safety, and quality of pharmaceutical products. This blog will explore the official standards of powders, sieves, and size separation in the context of pharmaceutical engineering, providing a comprehensive overview for professionals and enthusiasts in the field.

Official Standards of Powders

Pharmaceutical powders are classified based on their particle size, which is crucial for various applications, including drug formulation and manufacturing. The Indian Pharmacopoeia (IP) and other pharmacopeias provide specific standards for the classification of powders. According to the IP, powders are categorized into five types:

• Coarse Powder: Coarse powders are those that pass through a sieve with an aperture of 1.7 millimeters (No. 10 sieve) but are retained on a sieve with an aperture of 355 micrometers (No. 44 sieve). These powders are used in applications where a larger particle size is acceptable.
• Moderately Coarse Powder: These powders pass through a sieve with an aperture of 710 micrometers (No. 25 sieve) and are retained on a sieve with an aperture of 250 micrometers (No. 60 sieve). They are used in formulations where a moderate particle size is required.
• Moderately Fine Powder: Moderately fine powders pass through a sieve with an aperture of 355 micrometers (No. 44 sieve) and are retained on a sieve with an aperture of 180 micrometers (No. 85 sieve). These powders are suitable for applications requiring finer particles.
• Fine Powder: Fine powders pass through a sieve with an aperture of 180 micrometers (No. 85 sieve). They are used in formulations where a fine particle size is essential for proper drug delivery and absorption.
• Very Fine Powder: Very fine powders pass through a sieve with an aperture of 125 micrometers (No. 120 sieve). These powders are used in applications requiring extremely fine particles, such as inhalation products.

Here’s a table summarizing the official standards of powders as per the Indian Pharmacopoeia (IP), including the type of powder, aperture size, sieve number, and additional details:

Explanation of Terms

• Aperture Size: The size of the openings in the sieve mesh, which determines the particle size that can pass through.
• Sieve Number: Indicates the number of openings per linear inch of the sieve.
• Additional Details: Provides further specifications about the percentage of particles passing through secondary sieves.

Official Standards of Sieves

Sieves are essential tools in the size separation process, and their specifications are governed by official standards to ensure consistency and accuracy. The Indian Pharmacopoeia and other pharmacopeias provide detailed specifications for sieves used in pharmaceutical manufacturing:

• Number of Sieve: The mesh number indicates the number of openings per linear inch of the sieve. For example, a No. 10 sieve has 10 openings per inch.
• Nominal Size of Aperture: This refers to the size of the openings in the sieve mesh. The nominal aperture size determines the particle size that can pass through the sieve.
• Nominal Diameter of Wire: The diameter of the wire used to make the sieve mesh. This affects the strength and durability of the sieve.
• Percentage of Sieving Area: This is the ratio of the open area of the sieve to the total area. A higher percentage indicates a more efficient sieving process.
• Tolerance Average Aperture Size: This refers to the allowable variation in the aperture size. It ensures that the sieves meet the required specifications for particle size separation.

Mechanisms of Size Separation

Size separation in pharmaceutical engineering involves various mechanisms to achieve the desired particle size distribution. The primary mechanisms include:

• Sieving: Sieving is the most common method of size separation. It involves passing a mixture of particles through a series of sieves with different mesh sizes. The particles are separated based on their size, with smaller particles passing through the sieves and larger particles being retained.
• Elutriation: Elutriation involves the separation of particles based on their size, shape, and density using a stream of gas or liquid. The particles are suspended in the fluid, and the larger, heavier particles settle out while the smaller, lighter particles remain suspended.
• Cyclone Separation: Cyclone separation uses centrifugal force to separate particles based on their size and density. The mixture of particles is introduced into a cyclone chamber, where the centrifugal force causes the larger, heavier particles to move to the outer walls and be collected, while the smaller, lighter particles are carried away with the fluid.
• Air Classification: Air classification involves the separation of particles based on their size and density using a stream of air. The particles are introduced into an air stream, and the larger, heavier particles settle out while the smaller, lighter particles are carried away with the air.
• Centrifugation: Centrifugation uses centrifugal force to separate particles based on their size and density. The mixture of particles is placed in a centrifuge, where the centrifugal force causes the larger, heavier particles to move to the outer walls and be collected, while the smaller, lighter particles remain suspended.

Applications of Size Separation

Size separation is a critical process in pharmaceutical engineering, with various applications, including:

• Tablet and Capsule Production: Ensuring uniform particle size distribution is essential for the consistency and reliability of tablets and capsules. Size separation helps achieve this uniformity, ensuring that each dosage unit contains the correct amount of active pharmaceutical ingredient (API).
• Suspensions and Emulsions: In the production of suspensions and emulsions, size separation helps achieve uniform particle size distribution, which is crucial for the stability and efficacy of these dosage forms.
• Granulation: Size separation is used in the granulation process to produce granules of uniform size. This is important for ensuring the flowability and compressibility of granules during tablet compression.
• Powder Processing: Size separation is used in the processing of powders to achieve the desired particle size distribution. This is important for ensuring the uniformity and consistency of powdered pharmaceutical products.
• Quality Control of Raw Materials: Size separation is used in the quality control of raw materials to ensure that they meet the required specifications for particle size. This is essential for the production of high-quality pharmaceutical products.

Conclusion

Size separation is a fundamental process in pharmaceutical engineering, with far-reaching implications for the efficacy, stability, and quality of pharmaceutical products. Understanding the official standards of powders, sieves, and size separation is crucial for optimizing pharmaceutical formulations and ensuring the production of high-quality dosage forms. By mastering these concepts, pharmaceutical professionals can enhance drug performance and contribute to the advancement of pharmaceutical sciences.

For more regular updates you can visit our social media accounts,

Instagram: Follow us

Facebook: Follow us

WhatsApp: Join us

Telegram: Join us