Size reduction is the process which is used to reduce the size of different substances which are used for the preparation of medicinal products.Two types of methods are used for size reduction one is known as manual size reduction method and other is mechanical size reduction method.
In this article, we discuss the manual methods of size reduction.
Manual Methods Of Size Reduction
A conventional method used to reduce the particle size is known as manual method of size reduction where traditional types of mortar & pestle or slabs & spatula are used.
Manual size reduction methods are used on small-scale requirements of size reduction and the following methods are used,
- Trituration
- Levigation
- Pulverization
Trituration
Trituration is a manual method of size reduction where the particle size of solid substances is reduced by grinding, rubbing or striking in a mortar with the help of a pestle.
The process of trituration is also known as dry grinding as no liquid aid is used for size reduction by using the trituration process.
The mortar and pestle made of wood or porcelain is used for the size reduction of those materials which are not very hard.
To reduce the particle size of hard materials stainless steel mortar and pestle is used.
Example
To get the fine powders of clove it is crushed and ground in a mirror and pestle to reduce its particle size to get the finer or powder form.
Levigation Process
Levigation is the manual process of size reduction which resembles the trituration but the difference is that for levigation we use a few drops of liquid material as well.
Due to the addition of a few drops of liquid, the levigation process is also known as wet grinding.
The levigation process is defined as,
The process where the particle size of materials is reduced to a finer state by triturating it with some drops of liquid in which the material is insoluble by using mortar and pestle or a grinding slab with the help of a spatula.
Levigating Agent
The liquid used for size reduction during the levigation process is known as a levigating agent.
The following are the most commonly used levigating agents
- Water
- Glycerin
When a levigating agent is added to reduce particle size a paste-like material is formed which is converted into a smooth product by continuous trituration.
Pulverization Method
Pulverization method is also known as pulverization by intervention.
Pulverization method is also an example of wet grinding because for this we also use a solvent.
It is defined as
The process in which the size of solid materials is reduced to powder by triturating action in the presence of a solvent and the solvent used should be of such type that it can easily be evaporated at the end of pthe rocess.
Example
A common example is the size reduction of camphor using mortar and pestle. When we reduce the particle size of camphor without solvent the fine particles again adhere with each other and to overcome this issue we add a few drops of volatile solvent like chloroform and trituration of camphor in the presence of chloroform results in a finer state as the chloroform is evaporated at the end of this size reduction process.
Another example of size reduction by pulverization method is the size reduction of iodine in the presence of ether.
Conclusion
The manual size reduction method is used for small scale and dry grinding and wet grinding methods are used for this. The manual size reduction process is completed by using mortar and pestle or slab and spatula.
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