Use of the logarithmic functions of the relative retention values for choosing selective fixed liquid phases and characteristics of the functional groups of analyzed compounds

Graphic dependances of the difference of logarithmic functions of the relative retention values are suggested for characterizing org. compds. of various types. For example the relations of the type DI12 = f(DI34) are used, where DI12 and DI34 are differences of retention indexes of a given compd. on phases 1 and 2 and 3 and 4, resp. Points corresponding to compds. of the same class are located on graphs in certain characteristic regions, which can be used for the group identification of org. compds. [on SciFinder (R)

Use of the logarithmic functions of the relative retention values for choosing selective fixed liquid phases and characteristics of the functional groups of analyzed compounds

Graphic dependances of the difference of logarithmic functions of the relative retention values are suggested for characterizing org. compds. of various types. For example the relations of the type DI12 = f(DI34) are used, where DI12 and DI34 are differences of retention indexes of a given compd. on phases 1 and 2 and 3 and 4, resp. Points corresponding to compds. of the same class are located on graphs in certain characteristic regions, which can be used for the group identification of org. compds. [on SciFinder (R)

Description of the experimental dependence of the HETP on the linear velocity of the carrier gas in capillary gas chromatography

The equation most suitable for describing the data of the present authors and those reported in the literature on the carrier-gas-velocity dependence of the HETP for capillary chromatography was determined. The equation was validated for 67 gas-liquid and 32 capillary gas-adsorption chromatographic systems. The generalized Golay-Giddings equation was found to be adequate for 66-70% of the systems, whereas the Golay equation, only for 6-7%. It was concluded that the results obtained could be used to optimize analytical techniques

Use of equations for the description of experimental dependence of the height equivalent to a theoretical plate on carrier gas velocity in capillary gas-liquid chromatography

Optimal equation for fitting the experimental data on the height equivalent to a theoretical plate (HETP) versus carrier gas velocity in GLC was determined. The data obtained by authors and the literary data by other investigators were used for the comparative study of Van Deemter, Golay and the little known Golay-Guiochon equations. The Golay-Guiochon equation takes into account instrumental contribution and other sources of additional band broadening. Correlation coefficient R and Pirson's criterion χ2 were used as a criterion of the data correspondence to the equations. The Golay- Guiochon equation is the best for fitting of the experimental data in 71% considered examples, 19% experimental data may be fitted very precisely by the Van Deemter equation, the Golay equation is preferable for 7% experimental data only. Three percent experimental data may be fitted with the same precision by the Golay and the Van Deemter equations. The results obtained are of theoretical and practical interest. The Golay-Guiochon equation must be used more widely in analytical practice and physicochemical measurements. (C) 2000 Elsevier Science B.V

A comparative analysis of retention values obtained on fused silica capillary columns from various manufacturers

A comparative analysis of retention characteristics obtained on fused silica capillary columns available from various manufacturers is performed. The retention indexes for organic compounds of different chemical classes (octanol-1, 2,6-dimethylphenol, 2,6-dimethylaniline, naphthalene, methylpelargonate) are measured on the columns. The maximum variation in retention indexes is 1,63 i.u. on the columns coated with nonpolar stationary liquid phase (polydimethylsiloxane) and 16.26 i.u. on those coated with polar that (polyethylene glycol). The average maximum variation in the retention indexes obtained on the polyethylene glycol columns is more than that on the polydimethylsiloxane columns by a factor of 5. The established variation in columns selectivity from various manufacturers must be taken into account both in routine chromatography, in studies of physicochemical characteristics and when compiling of data bases

Description of the experimental dependence of the HETP on the linear velocity of the carrier gas in capillary gas chromatography

The equation most suitable for describing the data of the present authors and those reported in the literature on the carrier-gas-velocity dependence of the HETP for capillary chromatography was determined. The equation was validated for 67 gas-liquid and 32 capillary gas-adsorption chromatographic systems. The generalized Golay-Giddings equation was found to be adequate for 66-70% of the systems, whereas the Golay equation, only for 6-7%. It was concluded that the results obtained could be used to optimize analytical techniques

Capillary chromatography of hydrocarbons and their derivatives : application of SF6 as carrier gas [in russian]

Text in Russia

Capillary chromatography of hydrocarbons and their derivatives : application of SF6 as carrier gas [in russian]

Text in Russia

Effect of adsorption phenomena on the reproducibility of retention data for capillary columns

Precise measurement of the ratio of distribution coeffs. of compds. analyzed by gas chromatog. based on relative retention values is possible only if the contribution of adsorption is taken into account. Methods for evaluating the adsorption contribution in classical open capillary columns were elaborated and exptl. tested. For a std., a compd. is chosen whose adsorption on the capillary column walls can be neglected by comparison to its dissoln. in the stationary liq. phase. Equations are presented for the detn. of the ratio of the distribution coeffs. for compds. analyzed chromatog. in a gas-stationary liq. phase system and for the estn. of the contribution of the adsorption. Calcns. permit the detn. of the limiting value of the relative retention, which depends only on the soly. Adsorption changes the retention significantly even for compds. of medium polarity e.g. C6H6. [on SciFinder (R)