Chromatograms of Biological Stains on Acid and Basic Adsorbents

Abstract

A simple method of preparing chromatograms of mixtures of various biological stains on common acid and basic adsorbents is described. From the study of such chromatograms, three kinds of preferential adsorption can be recognized. (1) Due to the preferential adsorption of acid stains on basic adsorbent, a mixture of stains will separate itself into successive color bands on the chromatogram according to their individual acidity or basicity. The chromatogram, therefore, of a mixture of three stains—acid, neutral and basic—will appear on basic adsorbent according to the above order. The reverse order results if the acid adsorbent is used. The stains can be taken off from the adsorbents by shaking with proper solvents. (2) The components of some neutral stains or a mixture of some similarly charged stains can also be separated in a chromatogram. The order of appearance seems to be independent of the acid or basic nature of the adsorbents. This is similar to the chromatogram of leaf extract of plant pigments. (3) Finally, some mixtures of acid and basic stains do not follow their regular sequence of appearance on the chromatogram when adsorbed on magnesia. The reason for this anomaly is not clear, probably due to formation of adsorption complex.

This technic can be used to detect and separate mixtures of stains and to demonstrate the nature of adsorption and theory of staining. It can be used also as a preliminary test for the choice of solvent and adsorbent for chromatographic analysis. For the purpose of demonstration, an artificial cell can easily be made by impregnating talc (acid) and magnesia (basic) in collodion, in the form of nucleus, cytoplasm, etc., which is stained by following the general histological technic after the collodion is dried.