Éva János

Gas-liquid chromatographic analysis of dimedone derivatives of formaldehyde and other aliphatic aldehydes on capillary columns

Abstract The quantitative determination of small amounts of aliphatic aldehydes (formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde) in biological samples is difficult by the classical methods. The dimedone derivatives of these aldehydes were prepared and proved to be stable under the conditions of gas chromatography. The thermal properties of these derivatives were studied by thermal gravimetry, differential scanning calorimetry and thermal emission analysis, and the gas chromatographic peaks were identified by mass spectrometry. An analytical method was developed for the separation and determination of the dimedone adducts of aliphatic aldehydes by gas chromatography using capillary columns.

Gas chromatographic behaviour of carboxamide derivatives

Abstract Gas—liquid chromatographic retention indices of 28 substituted carboxamide derivatives were measured on apolar (Apolan 87) and polar (Carbowax 20M) stationary phases. Relationships were sought between these retention indices and the lipophilicities of the compounds. The influence of the structural elements on retention indices and lipophilicity was studied.

Possible relationship between lipophilicity and behaviour in reversed-phase thin-layer chromatography and gas-liquid chromatography

Abstract Gas-liquid chromatographic (GLC) retention indices of 31 aniline derivatives were measured on six columns of different polarity. Relationships between reversed-phase thin-layer chromatographic (TLC) R M values, log P values and GLC retention data (retention indices extrapolated to 0°C and retention index differences measured on different columns) were investigated by stepwise regression analysis. Significant relationships were found in only a few instances but the regression coefficients were not high enough for predicting lipophilicity. A dependence of the relationship between lipophilicity and retention data on the type of compounds was observed and difficulties with GLC as a technique for determining lipophilicity are emphasized. The influence of TLC systems on R M values, the influence of organic solvents on the partition coefficients and the influence of temperature and stationary phases on GLC retention indices are discussed.

Reversed-phase thin-layer and gas chromatographic retention behaviour of triphenylmethane derivatives

Abstract Reversed-phase thin-layer chromatographic (RP-TLC) R M values and Kovats retention indices ( I ) were determined for 26 triphenylmethane derivatives and their analogues (TMDs). The relationship between R M values and organic phase concentration in the eluent was investigated. A non-linear function having a minimum extreme value at about 60% acetone concentration was obtained. This phenomenon is related to the dual retention mechanism observed in reversed-phase high-performance liquid chromatography. The relationship between R M values and gas chromatographic retention indices was also studied. No significant linear relationship was obtained. The poor correlation indicates that gas chromatographic retention indices cannot be used for characterizing the lipophilicity of the TMDs, and RP-TLC is suggested for this purpose.