SynopsisRules were evolved to predict elution of linear, branched, and polar compounds in GPC, based on testing of 130 compounds. With these rules and in tetrahydrofuran solvent, data for all but a few compounds correlated onto a single calibration line. With small molecules, elution often changed, due to hydrogen bonding to the solvent; this occurred with alcohols, acids, and some chlorinated compounds, but not with mercaptans.One may conclude that structural elements were additive in their effect on elution volume in this study.Branched and linear isomers usually eluted a t about the same point.
Peak spreading in gel permeation chromatography has been studied with a range of gels including those whose permeation limit corresponded to about 103, 106, 108, and 109 molecular weight polystyrene. Peak spreading conformed to the equation YV2 = YM2 + YA2 + YI2 + YD2 + YS2, where YV is the peak width of a normal chromatogram, YM is the contribution due to the true molecular weight of the sample, YA is due to peak spreading in the apparatus, YI is spreading in the interstitial volume, YD is diffusional spreading due to time spent in the gel, and YS is due to sorption. Evaluating the appropriate parts of the equation leads to measures of the true molecular weight distribution and the contribution due to diffusion into and out of the gel. The data also allowed estimates as to the diffusional spreading with small molecules. With polystyrene having 100 000 molecular weight, diffusional spreading accounts for 80% of YV,2 but with small molecules the contribution due to diffusion was not detected.
Gel permeation chromatography is a special type of liquid‐solid elution chromatography based on the permeation of solute molecules into a rigid gel particle. The large molecules penetrate less into the small void spaces of the gel, and they are eluted first. Ideally, the entire separation is due to the size barriers that exist within the gel. Gel columns were readily calibrated with a series of polymer samples with a narrow molecular weight distribution. Elution curves of single components were found to be symmetrical, fitting closely the normalized probability function. Peak widths divided by their elution volumes correlated well with their heights. Complete resolution of the elution curve of a low polymer was demonstrated with these correlations. Calibration curves for polystyrenes and polyglycols were brought into coincidence by plotting elution volume against chain length on a logarithmic scale. These curves were not affected by column temperature changes or by changes to other good solvents as eluants.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.