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Study of retention and separation of pesticides in different modes of liquid chromatography
Dérerová, Tímea ; Kalíková, Květa (advisor) ; Riesová, Martina (referee)
4 Abstract This bachelor thesis is focused on a separation of six pesticides in reversed-phase and mixed-mode high performance liquid chromatography using Atlantis dC18, XSelect CSH C18, XSelect CSH Fluro-Phenyl and Atlantis Premier BEH C18 AX columns. The same manufacturing parameters - column and carrier particle dimensions opened up the possibility of their direct comparison in terms of retentivity and selectivity. The stationary phases were categorized using Walters test, in terms of hydrofobicity, silanol activity and efficiency. The analytes of interest were pesticides with a different mechanism of action in the environment. Two of them contained an acidic functional group that caused their elution at system void volume if pure water was used as aqueous part of mobile phase. For suppression of dissociation of acidic pesticides, the buffers, i.e., 10mM ammonium acetate, pH 4.7 and 10mM ammonium formate, pH 3.0 were used instead of pure water. Tested columns exhibited different retention and selectivity of analytes. For separation conditions optimization, an experimental approach, including changes in mobile phase composition and pH, and separation temperature, was used. Retention time, resolution and peak shape were all dependent on these chromatographic parameters. The retention of tested pesticides...
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Characterization and comparison of new reversed-phase HPLC columns
Putzová, Klára ; Kalíková, Květa (advisor) ; Kozlík, Petr (referee)
The aim of the bachelor thesis was to evaluate and compare interaction/separation properties of three chromatographic columns, namely XBridge C18, XSelect CSH C18 XSelect HSS C18, designed for reversed-phase high performance liquid chromatography. All the columns contain the same ligand, i.e. octadecyl but they differ in the stationary phase support. The columns were compared in terms of silanol activity, hydrophobicity, shape selectivity and efficiency. For this purpose, the simple chromatographic tests designed by Walters, Engelhardt and Galushko were used. Furthermore, the separation of five selected pesticides, namely acetochlor, fomesafen, isoproturon, metazachlor triflumuron, were optimized on tested columns in simple mobile phases composed of acetonitrile or methanol as organic modifiers and water. All the tested columns showed low silanol activity and medium to high hydrophobicity acording to the chromatographic tests used. The low silanol activity corelates with endcapping procedure used for all the columns. All pesticides were more retained in methanolic mobile phase due to the lower elution strength of methanol compared to acetonitrile in reversed-phase high performance liquid chromatography. The analysis time of separation varied for each column under the same chromatographic conditions. The...
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Characterization and comparison of new reversed-phase HPLC columns
Putzová, Klára ; Kalíková, Květa (advisor) ; Kozlík, Petr (referee)
The aim of the bachelor thesis was to evaluate and compare interaction/separation properties of three chromatographic columns, namely XBridge C18, XSelect CSH C18 XSelect HSS C18, designed for reversed-phase high performance liquid chromatography. All the columns contain the same ligand, i.e. octadecyl but they differ in the stationary phase support. The columns were compared in terms of silanol activity, hydrophobicity, shape selectivity and efficiency. For this purpose, the simple chromatographic tests designed by Walters, Engelhardt and Galushko were used. Furthermore, the separation of five selected pesticides, namely acetochlor, fomesafen, isoproturon, metazachlor triflumuron, were optimized on tested columns in simple mobile phases composed of acetonitrile or methanol as organic modifiers and water. All the tested columns showed low silanol activity and medium to high hydrophobicity acording to the chromatographic tests used. The low silanol activity corelates with endcapping procedure used for all the columns. All pesticides were more retained in methanolic mobile phase due to the lower elution strength of methanol compared to acetonitrile in reversed-phase high performance liquid chromatography. The analysis time of separation varied for each column under the same chromatographic conditions. The...
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