By measuring the surface

tension of a series of 12

diluted samples, the CMC

can easily be determined.  

Critical micelle concentration (CMC)

Surfactant/amphiphilic molecules contain both hydrophilic and hydrophobic parts. The hydrophilic part of the molecule prefers to interact with water while the hydrophobic part is repelled from water.

The molecules absorb at the air/water interface, decreasing the surface tension. As the interface becomes saturated, the molecules start to form aggregates or micelles in the bulk of the liquid, with the surface tension remaining constant. 

By measuring the surface tension of a series of 12 diluted samples (in Kibron Delta-8) from lowest to highest concentration (minimizing carry over) the critical micelle concentration (CMC) can easily be determined.