Monday, 4 March 2013

Solubility- Define and explain What is solubility?

Definition of solubility and explain what is solubility? - It is the quantity of a particular solute dissolved in a particular solvent to form a saturated solution under specified conditions of pressure and temperature. Solubility  is the property of liquid, solid or gaseous substances in which solute dissolved  in a given solid, liquid or gaseous solvent to form a solution.

It is divided into various types based on the amount of solute dissolve in a given solvent. 
Some of the types are as follows:
  1. Very soluble- Less than 1 part of solvent used to dissolve 1 part of solute.
  2. Free soluble- 1 to 10 part of solvent used to dissolve 1 part of solute.
  3. Soluble-  10 to 30 part of solvent used to dissolve 1 part of solute.
  4. Sparingly Soluble- 30 to 100 part of solvent needed to dissolve 1 part of solute.
  5. Slightly Soluble- 100 to 1000 parts of solvent  used to dissolve 1 part of solute.
  6. Very slightly soluble- 1000 to 10,000 part of solvents used to dissolve 1 part of solute.
  7. Practically insoluble- More than 10,000 parts of solvents are used to dissolve 1 part of solute.
Factors :
  1. Temperature
  2. Pressure
  3. Nature of solvent and solute
Technique or methods used to enhance or increase solubility are:
  1. Particle size reduction
  2. Solid dispersion
  3. Hot melt extrusion
  4. Nano suspension
  5. Hot melt method (Fusion method)
  6. Precipitation technique
  7. Solvent evaporation method
  8. Media Milling (Nanocrystals or Nanosystems)
  9. High pressure homogenization
  10. Combined precipitation and homogenization
  11. Cryogenic techinques
  12. Super critical fluid process
  13. Microwave irradiation method
  14. Ultra-Rapid freezing
  15. Spray freezing into vapor over Liquid
  16. Kneading Method
  17. Super critical anti solvent technique 
  18. Liophilization / Freeze drying technique
More Methods- Solubilization by surfactants, Solubilization by Salt formation, Nanotechnology approaches
                          Complexation, Modification of crystal habit by Polomorphs and Psedopolymorphs.

Reference -   (1)  Kumar A et al. / Pharmacie Globale (IJCP) 2011, 3 (03)
                              1 Pharmacie Globale© (IJCP), Vol. 02, Issue 03
                              Available online at