QSRR prediction of chromatographic retention of ethynyl-substituted PAH from semiempirically computed solute descriptors.

Retention prediction of 12 ethynyl-substituted polycyclic aromatic hydrocarbons (PAH) and their six unsubstituted parent compounds has been elucidated by the application of quantitative structure-retention relationship (QSRR) analysis. Retention data of the PAH were obtained from reversed-phase high-pressure liquid chromatography (HPLC) utilizing an octadecylsilica stationary phase operated under linear-gradient elution (60:40 water/acetonitrile to pure acetonitrile in 40 min). Six solute descriptors (moment of inertia, total energy, polarizability, ionization potential, dipole moment, subpolarity), computed from the optimized semiempirical AM1, MNDO, and PM3 solute geometries, were examined. Results from one-parameter QSRR analysis showed that retention of solutes was best predicted with solute polarizability as the parameter, computed from the AM1-(r = 0.969), MNDO-(r = 0.970), or PM3 (r = 0.967)-optimized solute geometries. From two-parameter QSRR analysis involving a size-specific parameter accompanied by a polarity parameter, it was found that solute retention was best reproduced by using solute polarizability and subpolarity as the parameters calculated from the AM1-(r = 0.983), MNDO-(r = 0.983), or PM3 (r = 0.984)-optimized solute geometries. On the basis of the results from both one-parameter and two-parameter regression analysis, the two-parameter QSRR equation with polarizability and subpolarity as parameters was found to be the best relation in relating solute molecular structure to retention under the HPLC conditions investigated. The results obtained in this study are of significance to predicting the identify of unknown product components based solely on parameters derived from solute structure.