Chapter 2
Some qualitative procedures can be used to discern emulsion type. One
simple method is contacting a drop of the emulsion with water or oil and observing
whether the external phase is miscible or not with it. However, this method can’t
distinguish simple and multiple emulsions.
O∕W
W∕O∕W
Figure 2.2 Morphologies of different type of emulsions [2]
The type of emulsion can also be determined by measuring its electrical
conductivity. The aqueous phase in an emulsion usually contains electrolytes and
therefore a relatively high conductivity should be observed (of order mS∕cm) for
O∕W emulsion with water as external phase. On the contrary, in most cases
non-polar liquids exhibit very low electrical conductivity (of order μS∕cm), and so
would W∕O emulsions with oil as external phase.