Ch. Lochmuller et al., HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY OF POLYMERS - RETENTION MECHANISMS AND RECENT ADVANCES, Critical reviews in analytical chemistry, 26(1), 1996, pp. 29-59
The high-resolution separation of polymer oligomers, their breakdown p
roducts and isomers is a significant challenge to modern separation sc
ience. The historically most successful methods are based on size excl
usion strategies and not mobile phase/stationary phase partition in th
e conventional sense. In the last decade significant progress has been
made in understanding the requirements for achieving elution chromato
graphy of high {> 5 kDa} molecular weight organic polymers ranging fro
m quite hydrophobic to quantitatively water soluble in character. This
paper discusses retention mechanisms, the dynamics of the partition c
hromatographic process, evidence for significant delays in polymer equ
ilibration to mobile phase conditions and the effect of the temperatur
e dependence of polymer solubility. Conventional chromatographic behav
ior is shown to obtain for the separation of polystyrenes, polymethylm
ethacrylates, polyethylene oxides and polypeptides if proper steps are
taken to carry out the experiment. The use of thermal gradients in sp
atial terms is shown to have significant value for achieving enhanced
separations.