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The effect of temperature on retention parameters of exemplary organic compounds in thin layer chromatography systems modified with metal ions

Flieger J., Szumiło H., Patel K.

Chemia Analityczna

2004

Vol. 49, No. 1

881-893

The influence of the temperature on retention of several aromatic hydrocarbons with polar groups was examined by thin-layer chromatography on silica gel and silica modified with zinc or nickel salts. Non-aqueous mobile phases containing ethyl acetate, tetrahydrofuran, dioxane, 2-pentanone and dichloromethane were used. Retardation factor (RF) of the solute molecules was measured at different temperatures from 269 K to 318 K. The changes of the temperature conditions resulted in differences in the migration rate and separation selectivity of the investigated compounds. Selectivity of the investigated systems was compared using the appropriate regression equations and graphically from RMI vs RMII plots. The effect of temperature on demixing phenomenon was also studied in frequently used chromatographic systems.

Zbadano wpływ temperatury na retencje wybranych węglowodorów aromatycznych z polarnymi grupami funkcyjnymi, stosując chromatografią cienkowarstwową na żelu krzemionkowym i żelu modyfikowanym solami cynku i niklu, przy użyciu niewodnych faz ruchomych zawierających octan etylu, tetrahydrofuran, dioksan, 2-pentanon i dichlorometan. Współczynnik opóźnienia (RF) analizowanych cząsteczek zmierzono w szerokim zakresie temperatur: od 269 K do 318 K. Zmiana temperatury procesu chromatograficznego powodowała wystąpienie istotnych różnic w tempie migracji i w selektywności rozdziału cząsteczek badanych związków. Selektywności badanych układów chromatograficznych porównywano przy użyciu równań regresji oraz graficznie z wykresów R(MI) vs R(MII). Zbadano także wpływ temperatury na zjawisko demiksji w badanych układach elucyjnych.

Indeksy topologiczne i ich znaczenie w badaniach chromatograficznych. Cz. 2

Pyka A.

Wiadomości Chemiczne

1998

[Z] 52, 9-10

727--754

The prediction of physicochemical and toxicological properties of organic compounds with selected topological indices have been reviewed in monographs and in dedicated articles The first topological indices used to the prediction of selected physicochemical properties (boiling point, heat of formation, heat of vaporization, molar volume, molar refraction) were: Wiener index, polarity number and Platt's index. The Wiener index has been continuously modified In recent years topological indices have come prominently to the fore on several different fronts. The prime reason for wide publicity accorded to these indices has been the remarkable ability to correlate and predict the properties of a vast range of molecular species. Topological indices based on the adjacency matrix, on the distance matrix and on information theory were applicable to the calculation of many physicochemical properties and to the evaluation of biological and toxicological properties of organic compounds. The procedure for calculating the topological indices is illustrated in this work by the calculation of the topological indices based on the adjacency matrix (the Gutman index M1), ; the Randić connectivity indices (0X, 1X, 2X, 0Xv, 1Xv, 2Xv); on the distance matrix (the Wiener index W); the Pyka indices (A, 0B, 1B, 2B); the Balaban index (IB); the Schultz Molecular Topological Index (MTI) for pentamethylenediamine. It should be noted that none of these topological indices yet described differentiates between d and l isomers. The procedure for calculating the optical topological index (Iopt) for d and l isomers is illustrated in this work by the calculation of Iopt for d- and l-alanine. Applications of these topological indices for the correlation analysis are discussed. The TLC, the HPLC and the GC retention parameters of different organic compounds were calculated using equations with the topological indices. As examples, selected correlation equations for calculation retention parameters in TLC, in HPLC, and in GC were shown in this work Definitions of the three-dimensional Wiener number 3W and the mean square distance topological indices of the s-th order D(x) were presented.