title: Adsorption equilibria of benzodiazepines on a hybrid polymeric chiral stationary phase.
abstract: The chromatographic behavior of a series of racemic benzodiazepines was evaluated under linear and nonlinear conditions on a new hybrid polymeric (DACH-ACR) chiral stationary phase (CSP). Differently substituted benzodiazepines were employed as probes to make hypotheses concerning possible molecular interaction mechanisms originating between target compounds and active sites on the CSP. Hydrogen bonds were found to be pivotal for chromatographic retention and chiral selectivity. The competitive effect from a mobile-phase (MP) modifier able to interact with the CSP through H-bonds was investigated. The performance of the polymeric DACH-ACR CSP for preparative purposes was also evaluated. The competitive adsorption isotherms of two benzodiazepines, lorazepam and temazepam, were measured at different MP compositions through the so-called inverse method. The adsorption data were fitted with a competitive bi-Langmuir adsorption isotherm. Enantiomeric separations under nonlinear conditions were modeled by using the equilibrium dispersive (ED) model of chromatography. Theoretical overloaded band profiles (obtained by solving the system of partial differential equations described by the ED model) matched, in a significantly accurate way, the profiles experimentally measured.
authors.affiliation: Department of Chemistry, University of Ferrara, via L. Borsari 46, 44100 Ferrara, Italy. cvz@unife.it
authors.forename: Alberto
authors.initials: A
authors.lastname: Cavazzini
authors.forename: Francesco
authors.initials: F
authors.lastname: Dondi
authors.forename: Stefania
authors.initials: S
authors.lastname: Marmai
authors.forename: Erik
authors.initials: E
authors.lastname: Minghini
authors.forename: Alessandro
authors.initials: A
authors.lastname: Massi
authors.forename: Claudio
authors.initials: C
authors.lastname: Villani
authors.forename: Romina
authors.initials: R
authors.lastname: Rompietti
authors.forename: Francesco
authors.initials: F
authors.lastname: Gasparrini
mesh_terms: D000327:Adsorption; D000465:Algorithms; D001569:Benzodiazepines / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D006860:Hydrogen Bonding; D008140:Lorazepam / Q000737:chemistry; D008962:Models, Theoretical; D013237:Stereoisomerism; D013693:Temazepam / Q000737:chemistry; D013816:Thermodynamics; D013997:Time Factors
chemical_list: D001569:Benzodiazepines; D013693:Temazepam; D008140:Lorazepam