Lipophilicity study of eight cephalosporins by reversed-phase thin-layer chromatographic method

The lipophilicity (R(M0)) and specific hydrophobic surface area for the representatives of four generation cephalosporins have been determined by reversed-phase thin-layer chromatography, and the effect of different mobile-phase modifiers (such as methanol, acetonitrile, acetone, 1,4-dioxane and 2-propanol) on the retention has been studied. The compounds studied showed typical retention behavior; their R(M) values decreased linearly with increasing concentration of the organic modifier in the eluent. The linear correlations between the volume fraction of the organic solvent and the R(M) values over a limited range were established for each solute, resulting in high values of correlation coefficients (>0.95 in most cases). R(M) values were determined by various concentrations of organic modifier, and the correlation obtained was extrapolated to 0% of organic modifier. Chromatographically established logP (R(M0)) parameters were compared with computationally calculated partition coefficients values (AClogP, ALOGP, KOWWIN, ALOGPs, XLOGP2, MLOGP and XLOGP3) and experimental octanol-water logP values (measured by the shake flask method). The received results demonstrate that RP-TLC may be a good alternative technique for analytics in describing the lipophilic nature of investigated cephalosporins as well as the activity.