Abstract: The effect of the varying operating parameters on the separation of steroids was studied by oil-in-water microemulsion liquid chromatography (MELC). The parameters included the surfactant concentration, the type of oil phase, the nature of organic solvent additives, and the pore size of the stationary-phase. The optimized conditions for the separation of 6 steroids were as follows: a Venusil ASB C18(T) column (5 μm, 30 nm, 250 mm×4.6 mm) was used at 35 ℃, the microemulsion mobile phase consisted of 30 g/L sodium dodecylsulfate (SDS), 0.8%(w/w) n-octane, 6.6%(w/w) n-butanol. The optimized method can be used for the separation, identification and simultaneous determination of steroids in bulk drugs and in pharmaceutical dose forms.

Key words: microemulsion liquid chromatography (MELC), separation selectivity, steroids , oil-in-water microemulsion