JAROSLAW POLANSKI¹, MIECZYSLAW SAJEWICZ¹, MAGDALENA KNAS¹, ANDRZEJ ZYWOCINSKI², MARCEL WELOE¹, TERESA KOWALSKA¹*
*Corresponding author
1. University of Silesia, Institute of Chemistry, 9 Szkolna Street, Katowice, 40-006, Poland
2. Institute of Physical Chemistry PAS, 44/52 Kasprzaka Street, Warsaw, 01-224, Poland

Abstract

The authors wish to draw wider attention to the following phenomena from the field of planar chromatography, which play a significant role in the analysis of chiral compounds and in exposing their ability to assume a propeller-like motion on the solid-liquid interfaces:
a. The microcrystalline chirality of silica gel, and
b. Lateral relocation of chiral analytes in planar chromatography systems with the silica gel stationary phases.
Apart from the warning referring to the negative impact of lateral relocation on detection and quantification of chiral compounds in the silica gel-employing planar chromatography systems, an interesting new possibility is signalized of using them for the demonstration and a thorough study of the propeller-like motion of these compounds on the solid-liquid interfaces.

EARLIER EVIDENCE ON LATERAL RELOCATION OF CHIRAL ROTORS IN PLANAR CHROMATOGRAPHY AND ITS POSSIBLE REASONS
In paper (1), we presented an overview of the striking phenomenon occurring exclusively in the planar chromatography systems, which is the deviation of the low molecular weight chiral analytes’ migration track from linearity. This deviation was item-wise signalized in our earlier papers (e.g., (2-6)) and declared as an unfavourable phenomenon, able to obscure, or even to fully obstruct the densitometric evaluation (and in the first instance, the densitometric quantification) of the thin-layer chromatographic results. Deviation of the analytes’ migration track from linearity is not the common retention behaviour of the most analytes and moreover, its extent cannot be in advance predicted, or estimated. In the case when chromatograms are scanned along a narrow line starting from the sample’s spotting place and going vertically to the mobile phase front, sample constituent with a migration trajectory deviated by several millimetres from linearity can either be erroneously declared as absent from the sample, or its quantification can be considerabl ...