title: Separation of steroids using temperature-dependent inclusion chromatography.
abstract: The influence of temperature on retention and separation of estrogens, progesterone derivatives and beta-cyclodextrin in reversed-phase high-performance liquid chromatography has been studied. Steroids were detected using direct UV detection at 240 and 280 nm. Detection of beta-cyclodextrin was achieved using a post-column indirect photometric method. Chromatographic experiments were performed using an acetonitrile-water mobile phase (30%, v/v) and a wide range of column temperatures from 0 to 80 degrees C with 20 degrees C steps. Linear Van't Hoff plots were observed for steroids and beta-cyclodextrin when an unmodified binary mobile phase was applied. The retention of steroids was strongly influenced by temperature when the mobile phase was modified with beta-cyclodextrin at a concentration of 12 mM. Particularly, for 17beta-estradiol and 20alpha-hydroxyprogesterone a strong deviation from the linear Van't Hoff plots and a remarkable affinity for beta-cyclodextrin was observed. Polynomial regression calculations were performed to fit the set of experimental data points. Using third-order polynomial equations, minimum separation factor values (alphamin) were calculated for temperatures from -10 to + 100 degrees C with 1 degrees C steps. The best chromatographic conditions for separation of multicomponent samples were chosen. A possible retention mechanism for solutes in the presence of macrocyclic additives is discussed. The results presented describe the role of temperature in high-performance liquid chromatography systems in which the mobile phase is modified with an inclusion agent.
authors: Medical University of Gdansk, Faculty of Pharmacy, Poland. pawel_k_z@hotmail.com
authors: P K
authors: PK
authors: Zarzyck
authors: R
authors: R
authors: Smith
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004967:Estrogens / Q000737:chemistry / Q000302:isolation & purification*; D011374:Progesterone / Q000737:chemistry / Q000302:isolation & purification*; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature
chemical_list: D004967:Estrogens; D011374:Progesterone