Size-exclusion chromatography in 1,1,1,3,3,3-hexafluoro-2-propanol.

1,1,1,3,3,3-Hexafluoroisopropanol is re-examined as an eluent for size-exclusion chromatography (SEC) of polyesters, nylons, and other polar polymers. It is shown that anomalous SEC behavior reported in previous literature can be eliminated by adding 0.01 M tetraethylammonium nitrate to the eluent. The eluent modifier does not affect the solution viscosity or root-mean-square radii of moderately polar polymers such as polyesters and nylons, but it does decrease these quantities for more polar polymers such as poly(ethylene oxide) and poly(2-vinylpyridine). More important, this salt appears to minimize repulsive interactions with styrene-divinylbenzene column packings that have contributed to non-ideal size-exclusion behavior. As a result, conditions are established that satisfy universal calibration.