Determination of ethinylestradiol and norethisterone in an oral contraceptive capsule by reversed-phase high performance liquid chromatography.
A specific and sensitive analytical method is described for the simultaneous determination of ethinylestradiol and norethisterone in a capsule formulation. These steroids, commonly used in oral contraceptives, were extracted from the capsules with acetonitrile and tetrahydrofuran. The steroids were then quantitated with a high performance liquid chromatograph using a ODS reversed-phase column and a ternary solvent system of water, acetonitrile, and tetrahydrofuran as the mobile phase. Several solvent systems for the mobile phase were examined using various C18 columns. The k' values for several steroids are reported, together with column performance parameters. It was found that columns from different manufacturers had significantly different behaviors with respect to separation parameters for these steroids.
D002214:Capsules; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003276:Contraceptives, Oral / Q000032:analysis*; D003280:Contraceptives, Oral, Synthetic / Q000032:analysis*; D004997:Ethinyl Estradiol / Q000032:analysis; D009640:Norethindrone / Q000032:analysis
D002214:Capsules; D003276:Contraceptives, Oral; D003280:Contraceptives, Oral, Synthetic; D004997:Ethinyl Estradiol; D009640:Norethindrone