DETERMINATION OF LIPOPHILICITY BY MEANS OF REVERSED-PHASE THIN-LAYER CHROMATOGRAPHY .1. BASIC ASPECTS AND RELATIONSHIP BETWEEN SLOPE AND INTERCEPT OF TLC EQUATIONS

The main aspects of the authors' chromatographic work are reviewed. Th e determination of lipophilicity by means of TLC techniques is mainly based on the linear relationship between R(m) values and organic solve nt concentrations in the mobile phase, as described by the TLC equatio n. The very good correlation between experimental and extrapolated R(m ) values supports the validity of the extrapolation technique. Another interesting aspect is that the nature of the organic solvent does not affect the measurement of lipophilicity. However, the main purpose of this paper was to re-examine all the TLC equations in order to assess whether the relationship between intercepts and slopes is a basic fea ture of the chromatographic determination of lipophilicity. The analys is of more than 700 TLC equations showed that the above relationship h olds only when dealing with series of strictly congeneric compounds. T he structural meaning of chromatographic congenerity is discussed.