title: Optimisation by experimental design of a capillary electrophoretic method for the separation of several inhibitors of angiotensin-converting enzyme using alkylsulphonates.
abstract: A statistical experimental design was used to optimise a capillary electrophoretic separation method for eight inhibitors of the angiotensin-converting enzyme: enalapril, lisinopril, quinapril, fosinopril, perindopril, ramipril, benazepril, and cilazapril. Because a free solution capillary electrophoresis system did not achieve a complete separation of these eight compounds in one run, the usefulness of alkylsulphonates as ion-pairing agents was investigated. After preliminary investigations to determine the experimental domain and the most important factors, a three-level full-factorial design was applied to study the impact of the pH and the molarity of the ion-pairing agent on the separation. Improved separations were obtained suggesting a favourable effect of ion-pairing interactions between analytes and the additive; however, it remained impossible to separate them all in one run. A combination of two systems was still necessary for the selective identification of these structurally-related substances.
authors.affiliation: Laboratory of Pharmaceutical Chemistry and Drug Analysis, Department of Pharmaceutical Analysis, Faculty of Pharmaceutical Sciences, Ghent University, Harelbekestraat 72, B-9000 Ghent, Belgium. sandra.hillaert@rug.ac.be
authors.forename: S
authors.initials: S
authors.lastname: Hillaert
authors.forename: Y
authors.initials: Y
authors.lastname: Vander Heyden
authors.forename: W
authors.initials: W
authors.lastname: Van den Bossche
mesh_terms: D000806:Angiotensin-Converting Enzyme Inhibitors / Q000302:isolation & purification*; D019075:Electrophoresis, Capillary / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D012015:Reference Standards; D012044:Regression Analysis; D013451:Sulfonic Acids / Q000737:chemistry*
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D013451:Sulfonic Acids