Summary.Possibilities have been studied of using a solvation model to predict the retention behavior of solutes in liquid chromatography mobile phases of water-acetonitrile and water-methanol with the organic solvent content varying from 1 to 100 vol%. Twenty-one test solutes, both aliphatic and aromatic compounds, have been selected on the basis of two-level factorial designs. Using the multiple linear regression analysis, regression coefficients, which are characteristics of the stationary and mobile-phase system, were calculated for different mobile phases in the solvation model. Regression coefficients have been used for the prediction of the retention behavior. Unbiased results have been obtained by using two sets, one training and the other the testing set. The predicted retention has been compared with the experimental data. The methanol-water system provided good results at low and medium methanol concentrations; the retention prediction was unsatisfactory for mobile phases containing more than 90% of methanol. The acetonitrile-water system yielded similar results, but the retention prediction ceased to be at acetonitrile concentrations greater than 80%. The retention has primarily been determined by cohesive and acid-base interactions. The dependences of the regression coefficients on the mobile-phase composition were similar for the acetonitrilewater and methanol-water systems.

The solvation descriptor L for 59 isomers of all C5 -C7 alkenes was calculated using two methods based on additive contributions of particular fragments in the molecule by the method of Havelec and Ševčík and the method of Platts and Butina. These descriptors were used to estimate the gas chromatography retention of alkenes on squalane and polydimethylsiloxane stationary phases. The retention was described better by the Platts-Butina method. Modification of the Havelec-Ševčík method by omitting the contribution for interaction of the cis isomers led to a substantial improvement in the estimation ability of the model. The modified Havelec-Ševčík method was found to be preferable for estimation of the descriptor L compared to the Platts-Butina method. A more comprehensive description of the retention of alkenes was achieved by inclusion of an additional descriptor E. This model with the descriptors L and E yielded better estimation for alkenes compared to the model with a single descriptor.