Sources of impurities | pharmaceutical inorganic chemistry

What is a impurity ?

Any foreign and unwanted matter present in our desired product is known as impurity.

Various types of impurities

There are various types of impurities in a product and these impurities need to be controlled for a better product. In order to control them we must know where these impurities come from.

Sources of impurities

(Watch this video for full explantation in Hindi ) 

1. Raw materials 

Raw materials usually present in final product as impurities.

 for example:- 

1. sodium compound have chloride as they are prepared from Nacl 

2. bismat salts have copper Lead and silver as impurities

3. zinc has arsenic copper and iron impurities

2. Reagents used

 Regents have to be removed by washing otherwise they would enter the final product as impurities.

for example:-  Ammoniated mercury is prepared by reacting Mercury chloride with ammonia, if precipitated ammoniated mercuric chloride is not washed then ammonium hydroxide may enter the final product.

3. Equipments and Apparatus 

Equipments and Apparatus used in the manufacturing process may contribute to various impurities in the final product

  when solvent react with metallic container in which the reaction is carried out traces of metal impurities are added in the solution it is known as leaching

 Equipments used in manufacturing constructed from glass silica Earthware, wood, rubber this can react with organic compound and come in the final product as impurity.

4. Impurities due to storage conditions

The conditions like temperature, humidity, light may contribute to impurities in the finished product as the product may undergo certainly chemical reactions

Most common decomposition reaction in the medical products are oxidation and phytochemical reactions

For example :-

1. Iodine reacts with rubber cork and some metals

2.  KOH , NaOH and Cacl2 ko and absorb moisture from atmosphere

3. KOH absorbs CO2

5. Environmental conditions

Environmental condition can affect the therapeutic value of drugs like temperature, atmospheric gases, moisture content, light and microorganism have their affect.

6. Solvent used in process.

The solvent used in the manufacturing process may contribute to various impurities in the final product.

Generally the solvent is water in major industrial purposes but this water needs to be free from impurities ( like calcium and magnesium impurities.

Various types of water

1. Tap water :- it contains calcium, magnesium, chlorides , sodium , sulphates as impurities

2. Softened water :- by passing tap water to sodium zeolites which remove divalent cations ( calcium and magnesium ) but still it contains 

3. Demineralized water :- passing tap water from ion exchange resins made water free from ions but can contain organic impurities.

4. Distilled water :- free from all impurities.