title: Orthogonality and similarity within silica-based reversed-phased chromatographic systems.
abstract: The starting point of this study was a current set of 32 chromatographic systems used to select initial conditions for method development to determine the impurity profile of a drug. The system exhibiting the best selectivity is then selected for further method development. In this current set eight silica-based phases are applied in conjunction with four mobile phases at different pH. In order to save time and resources, the possibilities for a meaningful subset selection were investigated. The most differing systems in terms of selectivity, in other words only the most orthogonal systems, need to be selected. Since the stationary phases are all silica-based, the selectivity differences are examined within a more homogeneous group than if, for instance, also zirconia- or polymer-based columns would be involved. To select the subset of systems also the best overall separation performances are taken into account. The selection is based both on the HPLC-DAD data of a generic set of 68 drugs, and on the LC-MS-DAD results for a mixture of 15 drugs, less different in structure. The orthogonality is evaluated using weighted-average-linkage dendrograms and color maps, both created from the Pearson-correlation coefficients r between normalized retention times r. The Derringer's desirability functions are applied to define the systems with the best overall separation performances. Proposals for different representative subsets of the initial 32 systems are made.
authors.affiliation: Department of Pharmaceutical and Biomedical Analysis, Pharmaceutical Institute, Vrije Universiteit Brussel-VUB, Chemo AC, Laarbeeklaan 103, B-1090 Brussels, Belgium.
authors.forename: E
authors.initials: E
authors.lastname: Van Gyseghema
authors.forename: M
authors.initials: M
authors.lastname: Jimidar
authors.forename: R
authors.initials: R
authors.lastname: Sneyers
authors.forename: D
authors.initials: D
authors.lastname: Redlich
authors.forename: E
authors.initials: E
authors.lastname: Verhoeven
authors.forename: D L
authors.initials: DL
authors.lastname: Massart
authors.forename: Y Vander
authors.initials: YV
authors.lastname: Heyden
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004364:Pharmaceutical Preparations / Q000302:isolation & purification*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012822:Silicon Dioxide
chemical_list: D004364:Pharmaceutical Preparations; D012822:Silicon Dioxide