Gel permeation chromatography. III. Molecular shape versus elution

Abstract

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.

Unit sheet weights of asphalt fractions determined by structural analysis

“…The GPC molecular size distributions for the two fractionated asphalts are shown with their equivalent molecular weights in Figure 2. These distributions may also be deter- GPC separations may be affected by the types of molecular material present (24)(25)(26)(27). A bulky paraffinic group may have the same size and thus the same elution volume as a compact aromatic group of a higher molecular weight.…”

Multimode separation of polycyclic aromatic compounds by size exclusion chromatography with poly(divinylbenzene)

“…A reason often proposed for this observation is the fact that nonplanar PAC are cyclic compounds with structures more compact than those of the calibration compounds, so they will elute later than predicted by a MW-based calibration curve (10,(31)(32)(33)(34)(35). Nevertheless, evidence is lacking that any general 0 Chemical suppliers: (AC) Aldrich Chemical Co., Milwaukee, WI; (AN) Analabs Div., Foxboro Analytical; (CA) Caledon-American, American Bioanalytical, Natick, MA; (CO) Columbia Organic Chemical; (CS) Chem Servies, Inc., Chester, PA; (LS) Lancaster Synthesis, Inc.; (SN) Synthetic chemical.…”

“…Molecular shape can contribute to anomalous PAC retention because PAC have more compact molecular shapes than the polymeric species usually used for calibration, causing them to elute later than calibration compounds of the same molecular weight. The effect of molecular shape on Ve can be significant for small molecules and has been studied (10,(31)(32)(33)(34)(35). "Chemical suppliers: (AC) Aldrich Chemical Co., Milwaukee, WI; (CC) Cambridge Chemical Co.; (CS) Chem Services, Inc., Chester, PA. 6 [Ve], elution volume.…”

Concentration effects in gel‐permeation chromatography

“…These results are consistent with the conclusions of Cazes and Gaskell'l and Hendrickson and Moore. 12 An approximately sigmoidal relationship exists between log of the solute size and elution volume with a gel of uniform pore size.13 I n practice, a combination of gel pore sizes is selected such that an essentially linear relation is obtained between elution volume and log (hydrodynamic volume) of the solute. This can be translated into a log (molecular weight)-elution volume curve to calibrate the particular column set if hydrodynamic volume and molecular weight are uniquely related.…”