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Two-dimensional (2D) TLC of eleven phenols has been performed on octadecyl-silica. The most efficient systems were selected by analysis of retention data obtained by one-dimensional chromatography using aqueous and non-aqueous mobile phases. Correlation graphs were plotted to illustrate the separation in the chromatographic systems examined. Complete separation of the phenols was achieved by using an aqueous mobile phase in the first dimension and a non-aqueous mobile phase in the second dimension. Statistical methods (principal-components analysis and cluster analysis) were used for better characterization of the TLC systems.

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Experimental R M values for a series of functionalized 2-alkylidene-4-oxothiazolidines and 1,2-dithioles have been determined by reversed-phase TLC on RP-18 silica plates. Binary mixtures of methanol and water, tetrahydrofuran and water, and acetone and water were used as mobile phases. R M 0 values were determined for these mobile phase mixtures by linear extrapolation to 0% ( v/v ) organic modifier. The lipophilicity, C 0 , was calculated as the ratio of the intercept and slope values. Chromatographically obtained lipophilicity data correlated well with calculated log P values.

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Experimental R M values for two series of β-diketonato complexes, M(acac) 3- n (phacphac) n and M(acac) 3- n (phSacphSac) n , where M represents cobalt(III) or chromium(III), have been determined by reversed-phase thin-layer chromatography on RP-18 silica with binary tetrahydrofuran-water, acetonitrile-water, and acetone-water mobile phases. R M 0 values were determined for the different mobile phase mixtures by linear extrapolation to 0% ( v/v ) organic modifier. Lipophilicity C 0 was calculated as the ratio of the intercept and slope values. Chromatographically obtained lipophilicity was correlated with calculated C log P values.

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JPC - Journal of Planar Chromatography - Modern TLC
Authors:
Tomislav Tosti
,
Gordana Rakić
,
Maja Natić
,
Dušanka Milojković-Opsenica
,
Suren Husinec
,
Vladimir Savić
, and
Živoslav Tešić

The chromatographic behavior of three biocidal technical materials, rodenticide active ingredients brodifacoum, bromadiolone, and coumatetralyl, and impurities present in the technical material was investigated by both normal-phase (NP) and reversed-phase (RP) planar chromatography. The research was carried out using thinlayers of silica gel, alumina, cellulose, and C 18 silica. Several solvents on their own or in various combinations and proportions were used for separation. The optimum chromatographic systems for separation of the substances from each other and from their impurities were selected. Under reversed-phase chromatographic (RPC) conditions a linear correlation between R M values and mobile phase composition was established. From results obtained, the lipophilicity R M ° and C 0 were determined. Possible separation mechanisms are discussed on the basis of the established retention behavior.

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