maximum additive concentration (MAC) Or simply solubilization capacity is The amount of solubilizate that can be incorporated into a given system at a fixed concentration upto a maximum that no more solubilizate can be incorporated furthur.
Factors of Solubility | solubilization capacity
Following are some key factors of Solubility/solubilization capacity.
Nature of the surfactant (surface active agent)
For a condition when solubilizate is located deep within the micelle structure the solubilization capacity increases with increase in alkyl chain length.this is valid upto a maximum alkyl length of 16 carbons; beyond that further increase will have a little effect on solubilization capacity. The effect of an increase in the ethylene oxide chain length of a polyoxyethylated non-ionic surfactant on its solubilising capacity is dependent on the location of the solubilizate within the micelle and varies correspondingly with changes in the micellar size. The aggregation number decreases with increase in the hydrophilic chain length so there are more micelles in a given concentration of surfactant and, although the molecules solubilised to micelle ratio decrease, the total amount solubilised substance per mole of surfactant may actually increase.
Nature of the substance dissolves
For a simple homologous series of solubilizates a decrease in solubilization occurs when the alkyl chain length is increased.A relationship between the lipophilicity of the solubilizate,
expressed by the partition coefficient of octanol-water system, and its extent of solubilization has been monitored for several surfactant systems.
Temperature
In most cases the solubilization increases as the temperature is increased.The effect is dominent with some non-ionic surfactants where it is because of increase in the micellar size with temperature increase.In some cases, solubilization increases with temperature as a direct proportion simply as an increase in kinetic evergy which onward leads to the amount of dissolution in the aqueous phase rather than in micelles.
Pharmaceutical importance of solubilization
The disinfectant properties of various phenolic compounds such as chlorocresol, chloroxylenol, cresol, and thymol with soap to form clear solutions is the solubalization action of these compounds.
