Application of Sol–Gels Modified with Natural Plants Extracts as Stationary Phases in Open-Tubular Capillary Electrochromatography

Ethanol extracts of three widely growing plants were added to silica sol–gel solutions, which were subsequently applied as wall surface modifiers in inner quartz capillaries. Modified capillaries were used for open-tubular capillary electrochromatographic separation of nucleotides and amino groups containing biological compounds (neurotransmitters, amino acids and oligopeptides). The experiments were performed at physiological pH 7.40, and eventual changes of effective mobilities were calculated. Specific compounds characteristic for each plant were tested as sol–gel additives as well, and thus-modified capillaries were used for the separations of the same analytes under identical conditions. The aim of this study was to find out possible interactions between physiological compounds and extracts of freely available plants anchorded in the sol-gel stationary phase in the flowing system. Even though the amount of the modifier in each capillary is very small, basic statistical evaluation showed some not negligible changes in effective mobility of tested analytes. These changes were bigger than ±5% for separations of nucleotides in capillaries with curcuma, Moringa or the mixture of synthetic additives as the sol-gel aditive, and for separations of amino compounds where these changes varying by additive, analyte by analyte.