Paper Chromatography of Alkaloids Using Liquid Ion Exchangers as Developing Solvents

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Abstract
The RF vs. pH relationships of a number of more important alkaloids were determined for several solvent systems of the type oleic acid + diluting solvent/aqueous buffer solutions. The chromatographic data seem to indicate a high solvent power of the organic phase, belonging to the class of liquid ion exchangers. The regular RF vs. pH relationships obtained can be quantitatively interpreted both by physical and by ion-exchange partition; the latter mechanism seems to be indicated by the exceptionally high extraction affinity of the organic phase (much higher, for instance, than for chloroform), difficult to explain by ordinary physical interactions. A marked effect of the diluting solvent on the solvent power and selectivity was found. In view of a certain parallelity of static (batch) extraction coefficients and chromatographic parameters, the latter can be employed for the estimation of suitable solvent systems for countercurrent separation of organic electrolytes on a preparative scale.