Selection of high-performance liquid chromatographic methods in pharmaceutical analysis. II. Optimization for selectivity in normal-phase systems.
Optimization of selectivity in normal-phase chromatography was studied. Using the same optimization criteria (Rs,min, Dmin, Rsb and Rsa) as in Part I the possible combination of "solvent strength" optimization by variation of the percentage of polar modifier in the less polar mobile phase and "solvent type" optimization by measuring the solvent selectivity of chloroform, acetonitrile, tetrahydrofuran and dioxane was examined. From the results it can be concluded that by replacement of medium-polarity solvents (chloroform, acetonitrile, tetrahydrofuran and dioxane) in the mobile phase, the selectivity of the separation can be significantly improved as the elution order is a function of solvent type belonging to Class P. In the separation of a steroid mixture dioxane provides the best properties for improving band spacing.
Gazdag
M
M
Chemical Works of Gedeon Richter, Ltd., Budapest, Hungary.
Szepesi
G
G
Fábián-Varga
K
K
D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004970:Estrone / Q000032:analysis; D004997:Ethinyl Estradiol / Q000032:analysis; D008656:Mestranol / Q000032:analysis; D009640:Norethindrone / Q000032:analysis; D009644:Norgestrel / Q000032:analysis; D013256:Steroids / Q000032:analysis*
D013256:Steroids; D004970:Estrone; D009644:Norgestrel; D004997:Ethinyl Estradiol; D008656:Mestranol; D009640:Norethindrone