Source of impurities , pharmaceutical Chemistry notes

Souce of impurities :

The type and amount of impurities present in the chemicals or pharmaceutical substances depeonds upon several factors. Some of such factors are .
Source of impurities , pharmaceutical chemistry notes

Raw materials employed in manufacturer :

When substances or chemicals are manufactured, the raw materials from which these are prepared often contain impurities. These impurities get incorporated in to the final product. Impurities like arsenic, lead, heavy metal etc. are present in raw materials and hence found in the substances. It is there fore employe pure chemicals and substances in raw materials for the manufacturering process.

Process ued in manufacturer :

There are a number of drugs and chemicals which are manufactured from different raw materials by adopting different process. Some impurities get incorporated in to the materials during manufacturering process. The type and amount of impurities present in the drug varies. Furthermore for certain drugs a multiple step synthesis procedure is involved, which produce intermediate compounds. The purification of the intermediate is also essential, other wise it get corporated in to the final product.

Chemical process :

In the synthesis of drugs many chemical reaction like nitration, halogenation, oxidation, hydrolysis etc. are involved. In these chemical reaction different solvent and chemicals are used. When chemicals reaction are carried out in vessels or containers the materials of the vessel are reacted upon by the solvents and chemicals and reaction products are formed. The reaction products that are derived from the plant material occur as impurities in the final product.

Storage conditions :

The chemicals or substances when prepared are stored in different types of containers, depending upon the nature of the materials and quantity. Various types of materials are used for storage purpose. They may be plastic, polythene, iron or stainless steel, aluminum or copper vessel. Reaction of these substances with the materials of the storage vessel may take place  and the products formed occurs as impurities in the stored materials. Alkalies stored in ordinary glass containers, extract lead from it which occurs in the final product.

Decomposition :

Some substances decompose on keeping and the decomposition is greater in the presence of light, air or oxygen. The result of decomposition causes the contamination of the final products. Many substances lose water of crystalisation when kept open , while deliquescent substances absorb water from the atmosphere, and get liquified. Crude vegetables drug are susceptible to decomposition. A number of organic substances get spoiled because of decomposition on exposure to the atmosphere. The decomposition products thus appear as impurities in the final products.
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