Substrate–polymer interactions in liquid exclusion chromatography (GPC) in N,N‐dimethylformamide

Abstract

SynopsisThe importance of nonexclusion effects in the GPC behavior of several stationary phases was investigated with DMF, 0.01M LiBr, as the mobile phase. Various low MW solutes and narrow MWD polymers, encompassing a wide range of polarities, were studied. The elution of the polymers was examined in terms of "universal calibration" behavior. Styragel and silanized glass both exhibit affinity for apolar polymers in DMF; for the former substrate this effect shows a strong inverse dependence on MW. As a consequence, application of polystyrene calibration curves to GPC analysis of more polar polymers with these substrates leads to overestimations of MW parameters. These errors are not corrected when universal calibration procedures are used. Ideal exclusion chromatography is exhibited by a number of polymers on untreated porous glass substrates. However, polymers with strong hydrogen-bonding functionality appear to be susceptible to marked adsorption in this system.

Determination of molecular weight of heparin by size exclusion chromatography with universal calibration

“…An accurate value of ðM w =M n Þ can be obtained only with the true M vs V e calibration curve for heparin. In principle, this could be obtained even with polydispersed samples of known M w or M n by an iterative procedure [31], but such samples were not available in the present study. For determination of the molecular weight of a heparin sample using this method, either of two approaches may be followed.…”

Estimation of Hydrodynamic Volume of Proteins Using High-Performance Size-Exclusion Chromatography and Intrinsic Viscosity Measurement: An Attempt At Universal Calibration

“…Before the appearance of HPLC, Reynolds, Tanford and co-workers (13)(14)(15)(16)(17) A method of calibration for hydrodynamic volume, termed the universal calibration procedure, proposed by Grubisic and co-workers (18) has been highly rated for various organic solvents examined by high-performance SEC (19)(20)(21)(22). There are several articles (23)(24)(25)(40)(41)(42)(43) on the validity of the universal calibration procedure for watersoluble polymers, however, there are few articles (37-39) that for proteins because of the lack of polymer standards having a narrow molecular weight distribution with a silica-basd column.…”

Determination of the Molar-Mass Averages of Random Poly(aspartate-co-lactide) Copolymers by Tuning the Ionic Strength of the Solvent

“…After heating the PALNa water solutions for 1 h at 50°C, the molar-mass averages of the copolymers decreased to a large extent. In the PALNa solutions in water, the highmolar-mass species are present, most probably due to the incomplete dissolution of the samples [20][21][22][23]25]. Based on the results obtained in water solutions of PALNa copolymers, we inferred that the intermolecular association prevailed over the polyelectrolyte effect.…”

“…With the addition of a simple electrolyte, i.e., NaCl, to water solutions of PALNa copolymers, the electrostatic, repulsive, ion-ion interactions can be prevented by screening the carboxylate ionic groups with sodium ions [18,19,[25][26][27][28][29]. Higher molar-mass averages of PALNa copolymers determined in pure water, as compared to the values determined in aqueous NaCl as a solvent (an order of magnitude of 100), suggest that the ions of the simple electrolyte not only shield the ionic groups of PALNa and thus prevent the polyelectrolyte effect, but most probably also specifically interact with the polar groups of the PALNa copolymers, thus preventing intermolecular ionic interactions and/or H-bonding, and, consequently, the association of the PALNa copolymers in water solutions [23,24].…”