Anales CIDEPINT 1997-98
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Examinando Anales CIDEPINT 1997-98 por Autor "Nardillo, A. M."
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Acceso Abierto Concurrent solution and adsorption of hydrocarbons in gas chromatographic columns packed with different loadings of 3- methylsydnone on chromosorb P(1998) Castells, R. C.; Romero, L. M.; Nardillo, A. M.Thermodynamic properties of solution in 3-methylsydnone (3MS) and of adsorption at the nitrogen/3MS interface were gas chromatographically measured for a graup of fifteen hydrocarbons at infinite dilution conditions. Retention voluntes were measured at five temperatures within the range 37-52°C in six columns containing different loadings of 3MS on Chromosorb P AW. Partition and adsorption coejficients were calculated and from their temperature dependence the corresponding enthalpies were obtained, although with considerable error; infinite dilution activity coejficients of the hydrocarbons in the bulk and in the surface phases demonstrated an strong correlation. Bulk activity coefficients in 3MS were very much smaller than those previously measured for the same solutes in formamide (FA) and in ethyleneglycol (EG), and were also smaller than what could be predicted on account of 3MS cohesive energy density as estimated from the quotient a/v13 (cr. surface tensión; v: molar volume). There was not such a large difference between the surface activity coefficients in the three solvents; furthermore, the quotients (surface activity coefficient/bulk activity coefficient) for a given solute in 3MS were twice as large as in FA and about three times larger than in EG. These results make evident the difficulties inherent in the prediction of surface phase properties from those in the bulk, and casi doubts on the pertinency of employing the surface tensión to compare cohesive energy densities of polar solvents with important Chemical dijferences. - Artículo
Acceso Abierto Integration of the equation of peak motíon in programmed-pressure and-temperatura gas chromatography(1998) González, F. R.; Nardillo, A. M.Numerical procedures for the estimation of the retention are compared considering the simultaneous programming of temperature and column head pressure , embracing issues from the mathematical basis to the practical aspects in the simulation of the chromatographic process by Computer. - Artículo
Acceso Abierto Retention in multistep programmed-temperature gas chromatography and flow control: linear head pressure programs(1998) González, F. R.; Nardillo, A. M.A comparative study of retention in different systems of flow control, that provide linear dependence with temperature of column’s head pressure, is performed by numerical simulation considering multistep (or multiramp) PTGC as the mosí general situation. Calculation algorithms for each flow control mode are developed on the basis of general retention equation and the only additional hypothesis that certain geometric parameters of the column remain practically constant along the program. Procedieres are individually contrasted with experimenta prior to application. The comparative view indicates that simple correlations ccmnot be obtained between retention times and temperatures in two different pressure Controls or pressure programs. It seems that numerical procedures are unavoidable when it is required the conversión of retention data from one chromatographic system to another with the same stationary phase. - Artículo
Acceso Abierto Theoretical and practical aspects of flow control in programmed-temperature gas chromatography(1998) González, F. R.; Nardillo, A. M.Behavior pattems for the temperature dependence of cohann head pressure and outlet volumetric flow rote are analyzed for some particular configurations of chromatograph's flow control system. Cuantitative prediction of this behavior, and specially it’s effect on gas hold up time, is evaluated the attention is centered on the application to PTGC retention simulation.