Multiple emulsions, also called complex emulsions or multiphase emulsions, include water-in-oil-in-water (W/O/W)-type and oil-in-water-in-oil (O/W/O)-type emulsions. W/O/W-type multiple emulsions, obtained by utilizing lamellar liquid crystal with a layer structure showing optical anisotropy at the periphery of emulsion droplets, are superior in stability to O/W/O-type emulsions. In this study, we investigated a two-step emulsification process for a W/O/W-type multiple emulsion utilizing liquid crystal emulsification. We found that a W/O/W-type multiple emulsion containing lamellar liquid crystal can be prepared by mixing a W/O-type emulsion (prepared by primary emulsification) with a lamellar liquid crystal obtained from poly(oxyethylene) stearyl ether, cetyl alcohol, and water, and by dispersing and emulsifying the mixture in an outer aqueous phase. When poly(oxyethylene) stearyl ether and cetyl alcohol are each used in a given amount and the amount of water added is varied from 0 to 15 g (total amount of emulsion, 100 g), a W/O/W-type multiple emulsion is efficiently prepared. When the W/O/W-type multiple emulsion was held in a thermostatic bath at 25°C, the droplet size distribution showed no change 0, 30, or 60 days after preparation. Moreover, the W/O/W-type multiple emulsion strongly encapsulated Uranine in the inner aqueous phase as compared with emulsions prepared by one-step emulsification.

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Gas chromatography (GC) of docosenoic acid (22:1) has been performed for the separation of positional isomers on the novel SLB-IL100 column with a highly polar ionic liquid stationary phase. A test mixture of 22:1 methyl esters prepared from total lipids of flounder was subjected to GC on a 60 m×0.32 mm i.d. column at an isothermal temperature of 150°C–180°C. On this column, all five positional isomers separated in the elution order of 22:1n-15, 22:1n-13, 22:1n-11, 22:1n-9, and 22:1n-7. The positional isomers, 22:1n-15, 22:1n-13, and 22:1n-11, unresolvable on conventional polar polymer phase columns, were almost completely separated from each other within 24 min at 170°C. The equivalent chain length values of 22:1n-11 to 22:1n-7 were parallel to those on polyethylene glycol and cyanopropyl polysiloxane columns, whereas 22:1n-15 and 22:1n-13 were relatively lower and closer to saturated 22:0 acid. Similar findings were also obtained