Examination of the Hydrophobicity of ACE Inhibitors and their Active Metabolites by Salting-Out Thin-Layer Chromatography

The behavior of five ACE inhibitors and their active degradation products in salting-out thin-layer chromatography (SO TLC) has been examined on silica gel, cellulose, and polyacrylonitrile (PAN) with aqueous ammonium sulfate solutions of different concentration as mobile phases. It was found that increasing the concentration of the salt in the mobile phase led to increased RM values for all the substances. Linear relationships were established between salt concentration and RM values and regression data of the plots obtained were used to determine the lipophilicity RM0 and C0. Lipophilicity determined in this way was correlated with calculated log P values. For comparison of these results with chromatographic behavior in conventional RP TLC, the examined substances were subjected to thin-layer chromatography on RP-18 silica gel with methanol—water mobile phases.