Test Analytes for Studies of the Molecular Mechanism of Chromatographic Separations by Quantitative Structure−Retention Relationships

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Abstract
Three model series of nonionized in water analytes are proposed for objective interlaboratory comparisons of effects on chromatographic separations of the stationary and the mobile phases by means of the analysis of quantitative structure−retention relationships (QSRR). Each series was designed specifically for a given general QSRR model by selecting the analytes whose properties were well reflected by the respective structural descriptors. Rules of a meaningful chemometric analysis were observed, and the structural information content was compromised with the length of analyte series. Three QSRR models were verified and are recommended for studies of molecular mechanism of chromatographic retention: the reduced linear solvation energy relationship-based model of Abraham, a model employing structural descriptors from molecular modeling, and a model correlating retention to the 1-octanol−water partition coefficient, log P. All the models were demonstrated to provide reliable QSRR equations for five sets of diverse retention data. These equations discriminate quantitatively individual chromatographic systems and are interpretable in straightforward chemical categories. In view of QSRR analysis, the retention processes clearly emerge as the net effects of fundamental intermolecular interactions involving the analyte and the components of chromatographic systems.