Experimental and Theoretical Study of Specific Retention Volumes in Mixtures of Polar and Non-Polar Stationary Liquids.

Abstract

Specific retention volumes, Vu, of monofunctional organic solutes have been measured in 1 -dodecanol, Iauronitrile, ranges of mixtures of each of these with squalane, and squalane. Results are presented as plots of V , against the weight fraction of hydroxyl group or nitrile group in the solvent. V,'s of alkane solutes decrease slowly with increase in weight fraction of polar group. In 1-dodecanol and its mixtures, alkanol solutes give steeply rising linear plots, and other polar solutes give curves concave to the abscissa. The plots for ethers and halogenates show maxima in V,. In lauronitrile and its mixtures, nitrile and nitro-solutes give steeply rising linear plots, and other polar solutes give curves concave to the abscissa. These results are correlated with a theory in which it is assumed that solutes and solvents interact in solution to form complexes in a manner obeying the Law of Mass Action. Procedures for semi-empirical calculation of specific retention volumes based on this theory are implicit.REVIOUSLY (11), we reported studies P of the effect on specific retention volumes, Vu, of different solvent polar groups a t the same molar concentration in the solvent, using a set of 1-hexadecyl derivatives as the stationary liquid solvents. We now report studies of the effect on retentions of the concentration of a given polar group in the solvent. As in the previous study, we used solvents in which the proportion by weight of polar group is always small, so that polar groups can be regarded as dilute species distributed in a matrix of methyl and methylene groups.We have measured V , for monofunctional organic solutes in l-dodecanol, lauronitrile (1-undecyl cyanide), ranges of mixtures of each of these with squalane, and squalane. The measurements are correlated with a theory in which retentions are studied as a function of the concentration of polar component of the solvent (Equations 26,29, and 31). EXPERIMENTALMixtures of solvents of accurately known weight proportions were made. Celite diatomaceous earth 100 to 120 mesh B.S.S. was impregnated with an accurately known proportion by weight approximately '/6 of each of the mixtures. The resulting materials were packed into U-shaped glass chromatography columns 6 feet X 4-mm. id., one column for each mixture. Columns were contained in vapor jackets, and temperatures were recorded to 0.1' C. Diurnal variations in temperature were noted and corrections based on them were made where necessary; these are not specifically referred to in the results. Nitrogen was used as the carrier gas, and vapors were detected by a catharometer held a t a constant temperature in a separate vapor jacket. In some of the work a flame ionization detector (Gas Chromatography Ltd.) was used.With columns of pure squalane, or mixtures containing much squalane and little polar component, there was evidence that retention volumes were influenced by adsorption on the support. To avoid this, the Celite was treated for a period of not less than 15 minutes in a stream of diniethyldichlorosila...

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