Multiple emulsions nomenclature

For systems as potentially complex as multiple emulsions, it is very important that a clear and consistent system of nomenclature be employed. For a w/o/w system, for example, in which the final continuous phase is aqueous, the primary emulsion will be a w/o emulsion, which is then emulsified into the final aqueous phase. The surfactant or emulsifier system used to prepare the primary emulsion is denoted as the primary surfactant. To avoid further ambiguity as to components or their locations in the system, subscripts may be used. For example, in a w/o/w system the aqueous phase of the primary emulsion would be denoted as wi and the primary emulsion as Wi/o. After the primary emulsion is further dispersed in the second aqueous phase W2, the complete system may be denoted W1/0/W2. In the case of an o/w/o multiple emulsion in which the oil phases are different, the notation becomes Oi/w/02. Additional refinements to fit even more complex systems, including the order of multiple emulsions, have been suggested. 

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