Concurrent Solution and Adsorption of Hydrocarbons in Gas Chromatographic Columns Packed with Different Loadings of 3-Methylsydnone on Chromosorb P
✍ Scribed by Reynaldo César Castells; Lilian Mónica Romero; Angel Miguel Nardillo
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 156 KB
- Volume
- 192
- Category
- Article
- ISSN
- 0021-9797
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✦ Synopsis
yleneglycol (EG), two solvents that shall be compared with Thermodynamic properties of solution in 3-methylsydnone 3MS in the present paper. While FA and EG are highly (3MS) and of adsorption at the nitrogen/3MS interface were gas associated liquids, 3MS is aprotic and the value of its Kirkchromatographically measured for a group of fifteen hydrocarbons wood g factor is 1.1 (1), indicating a random distribution of at infinite dilution conditions. Retention volumes were measured the molecular dipoles. However the cohesive energy density at five temperatures within the range 37-52ЊC in six columns (ced) of 3MS measured by the quotient s/£ 1/3 , as proposed containing different loadings of 3MS on Chromosorb P AW. Partiby Gordon (2), is apparenly very high and intermediate tion and adsorption coefficients were calculated and from their between those of FA and EG.
temperature dependence the corresponding enthalpies were obtained, although with considerable error; infinite dilution activity On account of its high dielectric constant and ced, 3MS coefficients of the hydrocarbons in the bulk and in the surface was a good candidate for promoting amphiphilic aggregaphases demonstrated a strong correlation. Bulk activity coeffition. However, Evans and collaborators (3) were unable to cients in 3MS were very much smaller than those previously meadetect formation of micelles in this solvent, a fact that these sured for the same solutes in formamide (FA) and in ethyleneglyauthors associated with the absence of hydrogen bonding in col (EG), and were also smaller than what could be predicted on 3MS. This made the measurement of free energies of soluaccount of 3MS cohesive energy density as estimated from the tion of hydrocarbons in 3MS interesting since, as Evans quotient s/£ 1/3 (s, surface tension; £, molar volume). There was pointed out, they are intimately related to the driving force not such a large difference between the surface activity coefficients for surfactant aggregation. This interest was reinforced by in the three solvents; furthermore, the quotients (surface activity the lack of information about the solvent properties of 3MS.
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.
Gas chromatography, using 3MS as the stationary phase, These results make evident the difficulties inherent in the predicoffers a series of advantages for these measurements. First, tion of surface phase properties from those in the bulk and cast chromatographic measurements can be effectively done at doubts on the pertinency of employing the surface tension to cominfinite dilution of the solute in the stationary phase. Second, pare cohesive energy densities of polar solvents with important a considerable gas-liquid interface is generated when the chemical differences.