Elution of lignin model compounds

Table III. Effect of Solvent Changes on Elution of Lignin Model Compounds and Polymers...

Apart from one compound (II), the lignin model compounds that had free phenolic groups eluted at close to the retention times predicted by the calibration curve from the polymer standards and not from the derive tized model compounds. This could simply be a result of the underivatized models having a similar variation in hydrodynamic volume with molecular weight as the polymer standards. However, it is to be expected that solvation of the underivatized model compounds should occur with THF as solvent (10), with hydrogen bonding of one THF molecule to each under-... 

Figure 3. Elution of derivatized ( ) and underivatized ( Q ) lignin model compounds with THF as eluant.

Table III describes the effect of solvent change on the lignin model compounds. None of the model compounds exhibited evidence of association all had unimodal elution in the different solvents. The Kp of the fully derivatized model compounds tended to increase as solvent polarity was increased, as had that of the polymer standards. As these are fully derivatized, relatively small molecules, the possibility for size change through interaction with the solvents is small. Increasing affinity for the column gel as the solvent polarity increased is the most probable explanation for their greater retention.

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