Investigation of the chromatographic process by the correlation between the R_M-values in adsorption and partition chromatography

Summary

Investigations were carried out on the correlations between the R_M-values measured in both adsorption and partition chromatography for some heterocyclic bases, 1-naphthylamine, 1-naphthol and phenol. Silica gel G and aluminium oxide G were used as the adsorbents while paraffin oil served as the liquid stationary phase in partition chromatography. Methanol, ethanol, isopropyl alcohol and acetone were used as the mobile phases. It was found that, similarly to the previous papers [1–3], the relationship$R_{M_i } = f(R_{M_i }^P )$ for all substances is linear described by the equation$R_{M_i } = a R_{M_i }^P + b$. However, in contrast to the previously investigated chromatographic systems [1–3], the constants a and b take negative values. This is due to the fact that in the adsorbent — mobile phase and liquid stationary phase — mobile phase interphase layers, contrasting types of molecular interactions prevail. In the polar adsorbent — apolar liquid stationary phase systems the values of the constant a for the substances belonging to the same compound class were more differentiated than those in the polar adsorbent — polar liquid stationary phase systems. The constants b are characterized by a smaller differentiation. The results of the present examinations on the correlations between the R_M-values in adsorption and partition chromatography show that these may be used in investigating the mechanism of the chromatographic processes.