Classification of terpene oils using the fish diagrams and the Equivalent Alkane Carbon (EACN) scale

The phase behaviour of ternary systems based on tetraethylene glycol monoalkyl ether (CiE4) as surfactants and a series of mono- and sesqui-terpenes as fragrance oils was investigated by resorting to the HLD (Hydrophilic–Lipophilic Deviation) concept. Each ternary system was studied by localizing the critical point (T*, C*) in the fish diagram and the terpenes were characterized by their Equivalent Alkane Carbon Number (EACN). EACN values have been rationalized by considering structural changes of the terpenes, such as number of carbons, branching, cyclisation, unsaturation and aromatisation. The C8E4/caryophyllene/water fish diagram has been established and compared with the alkane of closest ACN, i.e. hexane.